You are changing the argument to one of Sola Scriptura which the argument is not really about. But certainly we agree that Scripture is the canon by which dogma is tested against. You have no disagreement with me there.
The argument usually does boil down to sola scriptura.
However, as far as the early Christians I have a question for you. Do you believe that every Christian had a Gideons bible in their back pocket? The NT was written over a period of 40-50 years. How was the average lay christian to be informed of Scripture? Did everyone have a OT in their back pocket? Considering that 95% of the world population was illiterate in that day? How was the Gospel passed?
In this you greatly err. Let me emphasis to you again. It was Alexander the Great, the Greeks, that gave the world the Greek language. It was a universal language--thus the Bible was written in
Koine Greek--the Greek of the common person. It is more like 95% of the population were literate, not illiterate. Even the slaves could read. When the slave Onesimus went to Paul, and Paul advised him to go back to his master, Philemon, we have every evidence that Oneismus could read the Scriptures. He was a runaway slave. The world at that time was a very literate society and we have no evidence to believe the contrary.
The Gospel was passed on the very same way it is today--by evangelism, by the preaching of the word of God. Paul went into the market places and preached the Word of God. Sometimes he went into the synagogues and preached there. He preached wherever he had access: where the women gathered (with Lydia), in jail in Philippi to the Philippian jailor; Philip to the Ethiopian Eunuch in a chariot, etc. It didn't matter. They went every where and in every place preaching the word of God. Almost all were literate.
2 Timothy 4:13 The cloke that I left at Troas with Carpus, when thou comest, bring with thee, and the books, but especially the parchments.
--Paul asks for his coat (it was cold in Rome), the books (probably the OT), and the parchments (no doubt NT MSS that had already been written and were in his possession).
2 Peter 3:16 As also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.
--Peter recognizes NT Scripture already in existence, especially the Scripture of Paul.
Jude 1:3 Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should
earnestly contend for the faith which was once delivered unto the saints.
--The faith refers here to a body of doctrine that has been written down.
Jude was written in 70 A.D., when all but the writings of John had been written. He was referring to that which had been written by "the saints," the NT saints. They were to contend for that written NT doctrine that was written in NT MSS.
What many fail to believe is that through apostolic instruction the early church knew which books were inspired and which were not. The Canon was decided much earlier than the RCC would have you believe. Why are you and so many others deceived by the RCC that they were the ones that gave us the Bible. That is "bunk"!