That is not clear at all...If there was one who acted like a rock it was John...And then Paul...
What people fail to recognize is that while Jesus' ministry was so large that wouldn't be enough space to collect it all in writing, those things that were written were done so to give us enough information to be successful in knowing Jesus and attaining salvation...
For all we know, one of the lesser known apostles could have been more prominent than those written about...We have enough information to know that we are not to focus on any of the apostles but only Jesus...Just as the 'church' epistles were given to us by Paul, we are not to focus on Paul...
And what did Peter do that makes him outstanding among the other apostles??? Peter was used to show us how frail and unstable Christians and men who were apostles could be...Peter even proclaimed, 'don't bow down to me, I'm just a poor, dumb human like the rest of you'...
Certainly a far cry from the popes who have followed him.