Matthew 16:18 “..on this rock I build my church..”
Biblical pricipals are that the church has a head. Its first head was Peter. This “headship”, or papacy, was initiated by Jesus.
If you think I have misinterpreted the verse then Read Isaiah 22 and reexamine your opinion - especially with regard to the “keys” language in both Mt. 16:20 and Isaiah.
I just read Isaiah 22. It’s talking about Jesus dying for our sins.
“and the burden that was upon it shall be cut off”
Maybe the wrong reference?
The keys language originated with the Jewish practice of appointing “judges” who were in charge of and had the keys to the closet or storage room where all the scriptures and scrolls ie knowledge for living a Godly life and the laws of God were kept. The key unlocked the area that the knowledge to “follow the precepts of God” was stored. The “keys” the apostles received was the knowledge that they were in charge of to distribute to inform people of the gospel of Jesus.