Oh? It WASN’T James who made the decision as Scripture records?
I will give you partial credit for admitting that the early Church indeed had a pope. However, the Pope was St. Peter. Your answers also reveal a complete misunderstanding of the office of the Pope. The Pope is not the king of the Church, he is another Bishop, the Bishop of Rome and the first among equals.
Look first to the the way in which St. Peter's speech at the Council of Jerusalem begins and ends. By standing up to speak after the debate had subsided, Peter affirmed his authority and centrality. The silence after wards affirmed the finality of what Peter had just said; no one disputed his speech or his authority to make it. As frosting on the cake the witness of Paul and Barnabas, along with James’s speech, only reinforced what Peter said.
Not too many Protestants want to discuss Acts 15 in any great depth and are not too familiar with it, but in St. Peter's speech he first reminded the assembly that God spoke through him AND that he was the was the one through whom the Gentiles would hear the Gospel (Acts 15:7).
Lastly, when St. James spoke he first pointed to the words of St. Peter and then to the Prophets. He then definitively spoke of how to implement St. Peter's proclamation.
Peace be with you