The big picture - what is it? Is the good news that there is a perfect Saviour of the World or is the Gospel the good news of a perfect book about the matter?
If the latter is your view then it might be helpful to look more closely. As I have had to do myself in my own journey. There actually are variations in the documents and fragments which remain. Most do not remain. The vast majority of these discrepancies, imo, are minor. Thankfully. But there are thousands of them.
We cannot deny these facts. If we do, the latest skeptic or textual critic will declare: Ahh haa, silly Christian - I got you! I got you now! Your whole belief system in God and in the Bible fall to the ground... Game OVER.
Another issue which must be approached: Can we believe that the church fathers compiled the real canon (the group of authentic books in scripture) correctly... when they often held to other views which were erroneous?
The Almighty surely saw down through history and was aware of these things. He could have easily engraved the titles of real books of the Bible on a stone tablet or "golden plates". (Lucky Mormons...)
We also must remember that those "who turned the world upside down" were not carrying under their arms what most today believe to be a complete copy of the Scripture. Still, their success was huge!
Back to my question? What is the good news and why is it dependent upon a perfect book in order to be valid? God has already revealed Himself through creation, false though it be. And his laws are already written on our hearts. Yet we suppress them, Him, and are unthankful. Just as Romans chapter 1 reveals:
The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, since what may be known about God is plain to them, because God has made it plain to them. For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse. For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. Although they claimed to be wise, they became fools.
These are interesting facts. They suggest to me that God does not "let people off the hook" merely because they might find problems in the written forms of his revelation which are available today. The good news is that He is a personal loving God, each day making friends of his former enemies. Causing his sun to shine on the just and unjust.
These facts alone from the mighty letter to the Romans do not solve the riddle of church structure, I admit. Just trying to get the big picture rather than going straight to the details. The details are many.