The first condition of salvation is to keep the norm of the true faith and in no way to deviate from the established doctrine of the Fathers. For it is impossible that the words of our Lord Jesus Christ, who said, "Thou art Peter, and upon this rock I will build my Church," [Matthew 16:18], should not be verified. And their truth has been proved by the course of history, for in the Apostolic See the Catholic religion has always been kept unsullied. From this hope and faith we by no means desire to be separated and, following the doctrine of the Fathers, we declare anathema all heresies, and, especially, the heretic Nestorius, former bishop of Constantinople, who was condemned by the Council of Ephesus, by Blessed Celestine, bishop of Rome, and by the venerable Cyril, bishop of Alexandria. We likewise condemn and declare to be anathema Eutyches and Dioscoros of Alexandria, who were condemned in the holy Council of Chalcedon, which we follow and endorse. This Council followed the holy Council of Nicaea and preached the apostolic faith. And we condemn the assassin Timothy, surnamed Aelurus ["the Cat"] and also Peter [Mongos] of Alexandria, his disciple and follower in everything. We also declare anathema their helper and follower, Acacius of Constantinople, a bishop once condemned by the Apostolic See, and all those who remain in contact and company with them. Because this Acacius joined himself to their communion, he deserved to receive a judgment of condemnation similar to theirs. Furthermore, we condemn Peter ["the Fuller"] of Antioch with all his followers together together with the followers of all those mentioned above.— Formula of Pope St. Hormisdas, 6th century
Following, as we have said before, the Apostolic See in all things and proclaiming all its decisions, we endorse and approve all the letters which Pope St. Leo wrote concerning the Christian religion. And so I hope I may deserve to be associated with you in the one communion which the Apostolic See proclaims, in which the whole, true, and perfect security of the Christian religion resides. I promise that from now on those who are separated from the communion of the Catholic Church, that is, who are not in agreement with the Apostolic See, will not have their names read during the sacred mysteries. But if I attempt even the least deviation from my profession, I admit that, according to my own declaration, I am an accomplice to those whom I have condemned. I have signed this, my profession, with my own hand, and I have directed it to you, Hormisdas, the holy and venerable pope of Rome.
"The papacy for dummies": Christians believe Jesus was God and founded only one church. That church has a head bishop who under some circumstances has certain powers, such as to define doctrine. And what has he defined since roughly the time we clarified the extent/limits of those powers? Things about Mary that Catholics already believed. That's how it works. He's a caretaker, not a creator of doctrine.
19th-century Anglicans were admirably "conservative" like the Orthodox with their scruples about the development of doctrine (only a theory of Newman's, not our doctrine!) regarding the Pope. Really, I think that they imagined the 21st century as having the Episcopalians, the one true church (churchmen such as Charles Grafton believed that), holding fast to the ancient faith, creeds, apostolic ministry, morals, and all, while that madman in Rome did things such as attempt to ordain women and marry the same sex.
Western Catholicism without the Pope is a will-o'-the-wisp as the history of both Anglicanism and "independent" bishops shows, That said, I respect fellow Westerners who can't quite accept the Pope for theological reasons, not just bigotry like much of the Christian East: Continuing Anglicans and Missouri Synod Lutherans, for example, our estranged but still close cousins.
And... although classical Anglicans see us as in grave error (put on your fireproof suit to read the Thirty-Nine Articles), they claim the episcopate from us and recognize us, our bishops, our sacraments, as still Catholic too. Near me lives an Episcopal priest, an ex-Catholic, I have the utmost respect for; he is a marvelous Anglican apologist in C.S. Lewis' league. The sanctuary of his middle-of-the-road parish church has a mural from the 1950s depicting their understanding of holy orders that literally includes the Pope. I find that moving.
Pictured: St. Pius X, foe of Modernism (Protestantism on steroids, the heresy of heresies) and "founder" of the Russian Catholic exarchate (nec plus, nec minus, nec aliter: you don't have to give up your Orthodox customs to be Catholic).