So what is the position the Pope holds on behalf of Christ and the Catholic church?
Christ gave Peter the keys in Matt 16:19 with language of binding and loosing. This hearkens back to Isaiah 22:20ff.:
"In that day I will summon my servant, Eliakim son of Hilkiah. 21 I will clothe him with your robe and fasten your sash around him and hand your authority over to him. He will be a father to those who live in Jerusalem and to the people of Judah. 22 I will place on his shoulder the key to the house of David; what he opens no one can shut, and what he shuts no one can open."The Pope (=Papa, "father") is Christ's appointed steward. Like Eliakim he wields the authority of the King. When the regent is good and loyal, he is a peg in a firm place, a seat of honor (Isa 22:23-24)
BUT like Shebna, the regent who dares arrogate the power of the keys to advance himself God will cut down and depose (17-19, 25).
The Pope's authority comes from Christ whom he serves. He has none on his own.