I'm not sure where you're getting some of these ideas. Paul was very much a Jew. He trained under Gamaliel, one of the most prominent Jewish rabbis of the time. He did also have Roman citizenship, but those two things were not mutually exclusive.
Also, James, while prominent in the early church, was not in any sense Jesus's choice to lead the church. The closest thing to a single designated leader of the church was Peter though that is a point of contention between Roman Catholicism and Protestantism. Nowhere are circumcision or kosher foods required for Christianity, either.
Also, James, while prominent in the early church, was not in any sense Jesus's choice to lead the church. The closest thing to a single designated leader of the church was Peter though that is a point of contention between Roman Catholicism and Protestantism. Nowhere are circumcision or kosher foods required for Christianity, either.