Not true about Peter being the titular head of the church. As a matter of fact, that is why the Roman Catholic church split off. The Pope was always considered first among equals, NOT head of the Church. First among equals means if we're in your house, you speak first, but your vote does not supersede anyone else's. This is laid out in Scripture and was well known throughout the Church before the Great Schism. In Scripture: Peter was present at the Council of Jerusalem in Acts 15, but James, the Bishop of Jerusalem, presided, not Peter. In addition, Peter's opinion about the circumcision of the Gentiles did not prevail.

In addition - there were Bishops of Rome who were declared heretics by the Church in the first milennium. Among those was Honorius for his support of monotheism. How could one who is the "head of the Church" and incapable of error be condemned, by the Church, as a heretic?