“Follow me and I will make you fishermen of people.” (Mark 1:17)

Jesus stated this to Simon and his brother Andrew:
Later, as he was walking by the sea of Galilee, he saw Simon and his brother Andrew casting a net into the water – as they were fishermen.. (Mark 1:16)
We know from this and texts elsewhere that Simon is none other than Peter, who became a great teacher after Jesus left the planet:
As Jesus walked by the sea of Galilee, he saw two brothers – Simon who he named Peter and Andrew his brother – casting a net into the sea, for they were fishermen. (Matthew 4:18)

What does 'fishermen of people' mean?

Quite simply, it refers to passing on Jesus' teachings to others. But why is fishing being used metaphorically?

These brothers were fishermen, and were fishing by throwing nets out. The nets would capture those fish who were of a certain size and swimming within the vicinity of the net. Smaller fish could swim right through the netting.

In the same way, Jesus was passing out his teachings just as one would lay out a net. And those who were interested in regaining their relationship with the Supreme Being were receptive to those teachings - just as fish of a certain size would be caught within the net.

And those who were not interested in regaining their relationship with the Supreme Being would not be captured by Jesus' teachings.

Why would Jesus enlist these people so immediately in the service of spreading Jesus' teachings? And does this mean that Jesus was appointing them as his successors?

Just as many of the events are described throughout the Biblical scriptures - this is not the only exchange between Jesus and Peter and Andrew. Certainly, as it is detailed throughout the four gospels, Jesus also taught them many things, and they became committed to following Jesus.

But it is useful to note that Jesus was also a follower - of John the Baptist. Jesus was passing on the same teachings as John the Baptist taught - and Jesus asked his own students to pass on those same teachings - that God is readily available to us.

Furthermore, one might think that Peter and Andrew were being appointed to pass on Jesus' teachings, this is not the case.

Were the twelve apostles the only followers of Jesus who could teach?

In fact, while in Matthew it explains that Jesus appointed and sent out only the twelve apostles, in Luke it details that he sent out 72 of his students to pass on these teachings:
After these events the Master commissioned seventy-two others and dispatched them in pairs in advance of his appearance within the villages and places he was going to go. (Luke 10:1)
But it wasn't that they would just go to the towns. They were also sent to preach:
"Whenever you enter a village and they welcome you, eat what is set before you. Heal those who are sick and tell them, ‘The sanctuary of God is available to you.’" (Luke 10:8-9)
This completely changes the notion of "appointment" as most understand it. Some teach that Jesus appointed twelve special apostles, and these were the only ones able to represent Jesus' teachings. This is typically called the apostolic interpretation - which says that only Jesus' twelve apostles were empowered to carry on his teachings.

Jesus' sending out 72 disciples contradicts this interpretation. Sending 72 people denies the concept of "appointment" completely.  The Greek word ἀναδείκνυμι (anadeiknymi) is often translated to "appointed" in some translations. But it also means "to show" or "to proclaim" or "to lift up anything on high and exhibit it for all to behold" according to the lexicon.

This illustrates that Jesus requested that any of his serious students who have heard his message pass that message on to others:
One who listens to you listens to me; and one who rejects you rejects me. And one who rejects me rejects the One who sent me.” (Luke 10:16)
So we see that passing on Jesus' teachings as he was giving them was seen as passing on the teachings of the Supreme Being - "the One who sent me" as Jesus stated.

Was Jesus passing on the Prophets' teachings?

In other words, while Jesus was passing on the same teachings that his own teacher John had been teaching - and Jesus was asking his students to pass on those same teachings - Jesus indicated he was directly empowered by the Supreme Being: "the One who sent me."

In fact, this was also seen among the Prophets before Jesus. They passed on their teacher's teachings but they were empowered by the Supreme Being personally. For example, Joshua was Moses' student. When Moses passed away, Joshua resumed Moses' teachings. Consider how God personally empowered Joshua:
After the death of Moses the servant of the LORD, the LORD said to Joshua son of Nun, Moses' aide: "Moses my servant is dead. Now then, you and all these people, get ready to cross... Have I not commanded you? Be strong and courageous. Do not be afraid; do not be discouraged, for the LORD your God will be with you wherever you go." (Joshua 1:1-9 NIV)
Now consider Joshua's teachings to the people:
"But be very careful to keep the commandment and the law that Moses the servant of the LORD gave you: to love the LORD your God, to walk in obedience to Him, to keep His commands, to hold fast to Him and to serve Him with all your heart and with all your soul.” (Joshua 22:5)
So Joshua was passing on the teachings of his teacher Moses:
"If you carefully observe all these commands I am giving you to follow—to love the LORD your God, to walk in obedience to Him and to hold fast to Him—" (Deut. 11:22)
and of course, Moses' commandment:
"Love the LORD your God with all your heart and with all your soul and with all your strength." (Deut. 6:5 NIV)
In fact, this same teaching was also passed on - through the prophet lineage all the way through to John and Jesus - as Jesus also taught his students:
“The most important of all the instructions is, ‘Hear O Israel – the LORD our God is our only Lord and you shall love the LORD your God with all your heart, with all your soul and with all your mind and with all your strength’ – this is the most important instruction." (Mark 12:29-30)

How did Jesus come to know Moses' teaching? 

Because it was given to him through this lineage of teachers. It was passed on - not simply through the scriptures but also through the teaching lineage of Prophets that came through John the Baptist - as the scriptures were also handed down and interpreted through the lineage of teachers.

We can see the evidence that John the Baptist was part of this teaching lineage as he was raised and taught by his devoted father, Zechariah. Consider this portrayal of John:
At the time of Herod the ruler of Judea, there was a priest named Zacharias of the devotional order of Abijah. He had a wife named Elizabeth from the devotional heritage of Aaron. They were both devoted before God and observed without defect all the commandments and instructions of the LORD. But they had no children because Elizabeth was barren and they were both advanced in years. Once, while Zechariah was performing his priestly service before God within his devotional order – according to the custom of the devotional order, he was chosen by lot to go into the Temple of the LORD to burn incense. The entire assembly of people were praying outside at the time of the incense offering. Then an angel of the LORD appeared to him, and stood on the right side of the altar of incense. Zecharias was disturbed when he saw this and he was gripped with fear. But the angel spoke to him, “Don’t be afraid Zacharias, because your request has been heard, your wife Elizabeth will bear you a son and you will give him the name of John. He will bring you joy and delight, and many will rejoice at his birth. Because he will be great before the LORD. And he will not drink wine or liquor and he will be filled with the Holy Spirit even while he is in his mother’s womb. And he will turn many of the people of Israel back to the LORD their God. (Luke 1:5-16)
This last statement is significant:
And he will turn many of the people of Israel back to the LORD their God.
This illustrates what John the Baptist was doing - what his purpose was. Many have overlooked this mission of John - proclaiming his only purpose was to introduce Jesus.

Yet this is contradicted by the statements by the angel of the LORD above.

Such teachings ignore Jesus' teachings. But they also ignore how those teachings were passed on and empowered by the Supreme Being.

And this important element - understanding that Jesus was passing on the teachings as given by the Prophets before him - was also confirmed when John asked Jesus why he should be baptizing him:
But John forbade him, saying, “I need to be baptized by you, and yet you come to me?” Jesus answered him, saying, “Let it be so now, for it is appropriate in order to execute devotion.” Then he surrendered to him. (Matt. 3:14-15)
In other words, John recognized that Jesus was greater than he in his relationship with the Supreme Being, and thus was not feeling qualified to be Jesus' teacher. But Jesus insisted that John baptize him. Why? To illustrate that Jesus' teachings were coming through the lineage of God's representatives through the ages - which included Abraham, Isaac, Eli, Samuel, David, Solomon, Ezekiel, Jonah, Isaiah and others - which eventually led to Zechariah and then to John the Baptist.

But while it is obvious that John the Baptist took instruction from his father Zachariah, John, like the many other Prophets, also was directly empowered by the Supreme Being:
...during the high priesthood of Annas and Caiphas, the wisdom of God came in the wilderness onto John, the son of Zachariah. (Luke 3:2)
And we find many similar events portrayed in the Biblical scriptures - such as Jesus' own trip to the wilderness, and Moses' trip to the mountain and others - where the Supreme Being empowered them to teach on His behalf.

Yet we still find that they passed on the teachings of their teacher. For example, Moses may have instructed his students to make offerings, but we know from the texts in Genesis that Abraham was also making those same types of offerings - illustrating that Moses' instructions to make offerings to the Supreme Being reflected the teachings of Abraham to Abraham's students such as Isaac, who passed them on to the next generation.

Who authorizes God's representative?

This communicates clearly that the Supreme Being is consistent with His wishes, and what He empowers His representative to teach.

This illustrates the point hinted at above - that while the true teacher is passing on the teachings of their teacher - and lineage of teachers before them - they are empowered by the Supreme Being - not appointed or elected by a group of men.

But this concept of appointment should be understood. Today we find institutions electing and appointing their teachers from various political councils. After receiving seminary degrees, they are appointed or elected by a council of deacons or similar committees. These are typically chosen through a process of favoritism. This is another word for politics.

But these are not the processes upheld by Jesus when he stated, "Let it be so now, for it is appropriate in order to execute devotion."

What about paid preachers?

Why did Jesus receive baptism from John? Besides accepting John as his teacher, John the Baptist was not a professional teacher. John did not get paid a salary in order to teach.

In fact, this - being a professional teacher getting paid by salary - runs completely contrary to the notion of loving service. If a person is serving the Supreme Being they cannot accept a salary - because that salary makes them an indentured servant of the institution paying the salary. This in turn converts the teaching position into a political situation - because the teacher (professor of the seminary college or church preacher) is now obligated to those who control the purse strings - those in positions of power within that institution.
“No one can serve two masters: Either he will hate one and love the other or he will be devoted to one and despise the other. You cannot serve God and materialism." (Matt. 6:24 and Luke 16:13)
By becoming appointed by that institution and being paid a salary, these teachers are serving mammon - not the Supreme Being.

And this is the status of those who are elected/appointed by these church institutions to teach at a church in exchange for a salary - or those professors who teach at seminary colleges. First, in order to get the position they must become political - say the right things to impress the deacons or other council members. Then they must agree to abide by the rules set down by these deacons/councils in order to get appointed/elected.

And once they do get elected or appointed to the position, they must maintain their allegiance to the council or committee - or risk losing that position.

In other words, their teachings must be approved by the council or committee of people. If they start preaching something else, they will be fired.

This process is not empowered by the Supreme Being. The preacher is preaching what the councils - often appointed by the congregation - want them to preach. This essentially means that the preacher must preach what the people want them to preach or they lose their professional preaching position.

Is serving God an institution?

This system opposes the very fundamentals of service to the Supreme Being. And therefore those who are preaching within that system cannot be seen as representing the Supreme Being.

Rather, only a person who is passing on the teachings as heard from and consistent with the teachings of the representatives of God before them - and empowered by the Supreme Being to do so - can be accepted as teaching the Truth.

This has nothing to do with ceremony, title or other pomp and circumstance. It is the essence that is the heart of the matter. One must have a teacher before they can teach. And then one's teachings must be consistent with their teacher's teaching.

And their empowerment must come from their personal relationship with the Supreme Being - not by some political appointment.

And their service must not be engaged in exchange for a salary or other remuneration. If it is a service to the Supreme Being, then it is not a business relationship. It is a service of love, which is voluntary, not indentured.

This is communicated within the scriptures of the New Testament as illustrated above, and it is illustrated by the life of Jesus and the lives of the many other Prophets before Jesus.

And it is communicated within the teachings of Jesus - which were consistent with John's - as he also stated his direct empowerment by the Supreme Being - as "Him who sent me."

Does this mean that Jesus is God's representative?

And we know that by Jesus sending out all those who had seriously heard his teachings - including Simon and Andrew along with the rest of his 72 students - that God's representative also does not elect or appoint a specific person to be their successor.

Why? Why wouldn't Jesus select the next prophet from his group of 72 students to carry on his teachings and be the next "pope" or whatever?

Because Jesus was leaving this empowerment to the Supreme Being. Jesus was offering the confidential teachings to any student who became serious enough (and guided by God) to hear them. But then he left the rest up to the Supreme Being. He recognized this is the Supreme Being's mission.

This is confirmed by Jesus' prayer to the Supreme Being regarding his relationship with his students:
I have revealed Your Name to the people You have entrusted to Me from the material world: They were Yours and You entrusted them to me, and they have followed Your Teachings. Now they understand that everything You have given me comes from You. The words that You gave me I have given to them; and they received them and surely understood that I came forth from You, and they trust that You sent me. I pray for them. I pray not for the material world, but for them You have entrusted to me, for they are Yours. (John 17:6-9)