To establish a truth requires at least 2 reliable witnesses. How much time did old Augy spend at Corinth? "Being used by" -- what does that mean? My local church has a lot of books in its library which are used, even some writings by heretics. Once I was in a Presbyterian church service where the pastor read from a story about The 4th Wiseman. It went like this: The 4th wiseman left after the 3, and got off the direct road to Bethlehem. He had a bag of gold coins for the baby Jesus, but #4 kept running into people in need & giving them some coins. By the time he got to the baby Jesus, his bag was empty! (I think this was a story promoting salvation by works! read by an obtuse Calvinist!) So then I could go and say, "The Church of Philadelphia (Pa) uses The 4th Wiseman.
But I don't care what ol Augy said, "MY Sheep hear my voice." That means that Sheep (believers in Christ) intuitively know what is God's word -- they don't recognize stranger voices). And it is obvious that from the time the original recipients got a prophetic epistle from an apostle, they recognized it as God's Word. No one thought they should wait 300 years for some old religious fogies in robes & beards to tell them if it was God's word or not. Peter recognized Paul's letters at once. The 7 Churches of Asia Minor accepted John's Revelation at once. Your whole concept of canon is in error.
Heretics arose from the getgo. The early church was quickly corrupted (see 3 John & Diotrophes). Instead of having a plurality of elders=bishops, the monarchal bishop arose along with Patriarchs, & eventually a big papa in Rome -- none of this in the Bible. So they later debated the canon & made decisions on it. But they did not make God's Word.
Now you really have to make a decision on your theological epistemology:
Is it the RCC first or the Word of God first?
Do you recognize the Word of God & then try to prove the RCC is true?
Or do you recognize the RCC first & then try to prove the Bible is true from that?
Circular reasoning: A, therefore B. B, therefore A.
I start with God's word, self-evidently God's word.
Therefore the RCC is not true, as it is alien to the Word.
That is not to deny that whosoever believes in the Son of God (even if loyal to the Pope) has everlasting life. Believe = trust in Him as SAvior (not mere chance-giver).