8 For I tell you that Christ has become a servant of the Jews on behalf of God’s truth, so that the promises made to the patriarchs might be confirmed
I think this confirms that Jesus was sent to teach the Jews. The Jews being one of the only monotheist religions. What is unique about Jewdaism is that it is both a religion and an ethnicity. That is WHere St Paul's work becomes important in exporting the message also to the Gentiles. The Jews were (and are) the "chosen people" so it was written that the Messiah would be a Jew and the Jews would convert the world to monotheism.
5 These twelve Jesus sent out with the following instructions: “Do not go among the Gentiles or enter any town of the Samaritans.
Ithink this also illustrated what I said previously. That the Jews were keepers of the Law and were the original fruit of the vine. It wasn't until later when Pagans the the Greeks and Romand and apostates like Paul would be grafted in. I still don't think that the first Gentile Churches didn't believe that faith should bear fruits and it wouldn't be enough to simply proclaim Christ but also follow his teachings. Christ's teachings were based on Jewish Law.
24 He answered, “I was sent only to the lost sheep of Israel.”
I think this also illustrates that not only Christ was the messenger to the whole world but the Christian Jews would carry out his work. St Paul did this very effectively however, I still don't believe that St Paul's teachings should be held above any other Apostle's teachings. Only that each Apostle had unique talents, some Apostles' words resonated with one group and some others.
I think this also illustrates that Christianity was based on Jewish Law, not the letter of the Law but the spirit of the Law is what Christ came to say. By making following Jewish Law a non-requirement, it was easier for Paul to convert Gentiles.
But back to the title of the thread......Baptism was a requirement of Jews which Jesus followed. It is only easy to conclude that if Jesus felt he was required to be baptized, and desired to be baptized, washing away the old and agreeing to be obedient to God we should also.
I believe it is still the case that Peter did not want to offend the followers of James and wanted to stay relevant to the Jewish Christian movement, he yielded to the Jewish law that he lived all of his life. He was chastised by Paul for his obedience to the law and Peter accepted that Pagans would likely refuse to follow Jewish Law, he also caught to make his teachings available to Gentiles as well. However, in that moment referred to by Galatians, I believe that St Peter firstly wanted to keep the peace as in those violent times apostates were subject to be executed. So I think St Peter very wisely made his appeal to both Jews and Gentiles. The Gentiles, having no dietary restrictions, it seems that he respected and did not want to defile the table of those people who kept Kosher. We also see that after St Peter founded the Roman Church, his students and the students of his students converted the Roman Empire which was Pagan. Not wanting to offend either side (Jew or Gentile), he made his message acceptable to everyone universally, that is why Catholic means (universal) it was and still is the universal church open to everyone, Jew or Gentile.
Apologies for droning on and on, I just wanted to give a detailed explanation of why I interpret the Bible versus you so kindly quoted the way I do.