Paul went to Peter to ensure that his Gospel accorded with that of Peter (and the eleven) (Galatians 1). If Peter was simply one of the twelve, why go to him? As to authority, Paul went to Jerusalem to get an answer on the circumcision question. (Acts 15) Note that the scriptures were of no help to Paul. At the first council, Peter spoke and the assembly remained silent. James was also prominent, as he was the first Bishop of Jerusalem.
I don’t agree with your conclusions you’ve drawn from those two passages. Especially Galatians…
11** When Cephas came to Antioch, I opposed him to his face, because he stood condemned.** 12 For before certain men came from James, he used to eat with the Gentiles. But when they arrived, he began to draw back and separate himself from the Gentiles because he was afraid of those who belonged to the circumcision group. 13 The other Jews joined him in his hypocrisy, so that by their hypocrisy even Barnabas was led astray.
2:14 When I saw that they were not acting in line with the truth of the gospel, I said to Cephas in front of them all, “You are a Jew, yet you live like a Gentile and not like a Jew. How is it, then, that you force Gentiles to follow Jewish customs?
15 “We who are Jews by birth and not sinful Gentiles 16 know that a person is not justified by the works of the law, but by faith in Jesus Christ. So we, too, have put our faith in Christ Jesus that we may be justified by faith in[d] Christ and not by the works of the law, because by the works of the law no one will be justified.
17 “But if, in seeking to be justified in Christ, we Jews find ourselves also among the sinners, doesn’t that mean that Christ promotes sin? Absolutely not! 18 If I rebuild what I destroyed, then I really would be a lawbreaker.
19 “For through the law I died to the law so that I might live for God. 20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!”
Here we see Paul clearly preaching to Peter.
Also, Acts 15 clearly shows an early separation:
38 But Paul thought not good to take him with them, who departed from them from Pamphylia, and went not with them to the work.
39 And the contention was so sharp between them, that they departed asunder one from the other: and so Barnabas took Mark, and sailed unto Cyprus;
40 And Paul chose Silas, and departed, being recommended by the brethren unto the grace of God.
41 And he went through Syria and Cilicia, confirming the churches.
They separated over a disagreement and yet later Paul states in his letter 2 timothy 4:11Only Luke is with me. Get Mark and bring him with you, because he is helpful to me in my ministry.
The same Mark even wrote the Gospel we have today!
You see, we should be allowed to disagree on little things like we do today and not claim that we’re separated brethren just because of our tiny disagreements. I think claiming that this or that person is more important is what separates you and I.