We also are in the same boat with the pillars. They say, apparently, they were apostles but are they?According to Paul's account in Galatians, he was not made an apostle by authorization from people in Jerusalem. Paul never was an apostle in the sense that others were, at all. He only says he was
The gospels give these apostles the hardest of times. No realising who Jesus was, or understanding his mission, denying him, arguing, abandoning him (in John) etc. This serves to undermine anyone who might have claimed some kind of continuation. A new line is being drawn. Just as Paul has his conversion so does Peter in Acts. So the 'before' is murky indeed
Even if James was the literal brother of the Lord, it means nothing when the gospels, like Mark, have Jesus saying his disciples are his true brothers
My point is, the schema that has the 'Jerusalem church' somehow representing the original movement is just as questionable as Paul's claim to a direct revelation. If Galatians is historic then it only means Paul encounters folk who are like him, claimants to be representatives. And my point stands that if Paul denies prior association with the movement to the pillars it suggests the pillars are not representing the original movement but there is a prior split or schism we are not seeing