Why the Fisherman?
Jesus was not starting a new religion, he came to lead the Hebrews back to GOD. All the people of Jewish hierarchy were well in trenched in the dogma they established and perpetuated.
Most of the augmented law of The Pentateuch had been corrupted to benefit the religious and secular Jewish leaders. The Jewish fisherman and other laymen understood “The Law” and traditions but were open to what a new Rabi (Jesus) had to say.
Matthew 23:1-39 ESV
Then Jesus said to the crowds and to his disciples, “The scribes and the Pharisees sit on Moses’ seat, so practice and observe whatever they tell you—but not what they do. For they preach, but do not practice. They tie up heavy burdens, hard to bear, and lay them on people’s shoulders, but they themselves are not willing to move them with their finger. They do all their deeds to be seen by others. For they make their phylacteries broad and their fringes long, …
Sinners and Tax Collectors?
Matthew 9:11 ESV
And when the Pharisees saw this, they said to his disciples, “Why does your teacher eat with tax collectors and sinners?”
Mark 2:17 ESV
And when Jesus heard it, he said to them, “Those who are well have no need of a physician, but those who are sick. I came not to call the righteous, but sinners.”
OK John the Baptist offered a way for the Jews to repent and regain favor with GOD and apparently most rejected him. Jesus came to offer the same to all the Jewish people but it seems only sinners and tax collectors heard and obeyed. Only a very few leaders responded as Nicodemus had. Eventually the hardened hearts resulted in the Crucifixion of Jesus and the offer of salvation to all people (including Gentiles).
SONG: Open the Eyes of My Heart by Michael W. Smith, lyrics included.
Acts 28:28 ESV
Therefore let it be known to you that this salvation of God has been sent to the Gentiles; they will listen.”