Peter was clearly given leadership. This is clear, throughout the century's. I could do more than my Priest with teaching and evangelization, but does that make me his leader? How about one of your "Priest" doing more than the "Archbishop of Canterbury" with humanitarian work, or theological work, does that make the "Priest" the "Archbishops" leader? Peter, being the leader, was the oversee of the Council. There is nothing to indicate that James was the primary oversee of the council in Acts 15. However, there is much to show that Peter was. But, even if James was, it wouldn't go against Petrine leadership, seeing that Jerusalem was in James territory, and Peter could give James the right to oversee the council, though, Peter could take over at anytime because he was clearly over James.