*****Where is that found in Scripture?*****
1 Timothy 3:15
But if I tarry long, that thou mayest know how thou oughtest to behave thyself in the house of God, which is the church of the living God, the pillar and ground of the truth.
First came the Church, then from that Church came Scripture.
Notice that one of the first things the Church did when no longer under threat of persecution was to come together to formalize the Canon of Scripture.
******Like I’m going to believe unsubstantiated claims of some organization that wants to claim authority over everyone on the planet in regards to spiritual matters.*****
Not everyone on the planet, just those who believe in Christ.
Whether one chooses to believe or not believe is of no accord to me. History is what it is and the claim of unsubstantiation by anyone is not valid in light of the facts.
And there is no legitimate basis for them claiming that it meant them retroactively.
That's just them trying to put their claim of being the source of Scripture and spiritual authority beyond any doubt, and considering the history of the RCC, there's no reason to suspect or conclude that they are God's instrument on this earth.