The NT was not written down for decades after Christ’s death and resurrection - it took centuries after it was written to agree on which books should be included or excluded
While the apostles were on earth, the churches throughout the Roman empire were (a) receiving their direct oral teachings, (b) receiving copies of their epistles which were to be circulated among all the churches, (c) as well as collecting the "Holy Scriptures" (the Tanakh whose canon was already established).
Peter wrote his second epistle around AD 68 in which he said that all of Paul's epistles (51% of the NT) were also Scripture. He also said that his own epistles were divinely inspired ("a more sure word of prophecy"). So how did Peter know of all of Paul's epistles unless he had personally read them? But he also indicates that others had read them. That tells us that Paul's epistles were already in circulation within the churches, and also that some were wresting those Scriptures. See 2 Peter 3.
By the end of the first century, the whole Bible had been completed. Before the end of the second century, there was a canon of the New Testament (the Muratori Canon), as well as a Syriac translation of the almost the whole Bible (known as the Peshitta).
So how was the Peshitta put together unless the whole Bible was not already known and being read by the early Christians? While 5 or 6 of the NT books were called "disputed writings" (antilegomena) that was not meant as heretical or false, but simply uncertainty among some Christians whether they were canonical. Later on, those books were included. So it is a greatly exaggerated idea that the Bible was not complete for many centuries, and that the Catholic Church put the Bible together.
What is absolutely certain is that the Hebrew canon EXCLUDED the Apocrypha. Which means that there is no such thing as a Deutero-Canon. Even the Catholic scholar Jerome understood this when translating the Latin Vulgate.