I have heard the Bible story was only written hundreds of years after all these miracles etc. etc. are supposed to have happened.We know Christmas was the ancient Viking Yule feast.
and I think you are generally correct. We "modern" people only ascribe reliability to the written word. But the written word has only been around for the majority of people since the invention of the printing press in the late 15 century. There were, of course, hand copied documents before that. But the reliability of "oral" information had been relied upon for centuries before writing became even fairly common. The vast majority of information considered vital to whichever civilization you want to pick, from Babolonian to Roman Mystery religions, relied on the accurate memorization and recitation of information. Even here, in our own time and place, I am a member of an organization (Freemasons)that uses "ritual" information that has not been written down. Rather, the information has been passed down orally for more than 300 years, with little change. And I am not talking about small amounts. Thousands of words in hundreds of sentences are part of our "library". Because modern man has learned to use the very accessable technology of writing, we have lost the ability to memorize data and information. But the ancients were able to memorize and pass down information with little to no "errors" for many centuries and THAT was considered normal. So, after a few hundred years of oral recitation of the Gospel was done, people finally DID start writing the information down, as writing AND reading became more commonplace. But for the examples outlined above, the writing of the Gospels centuries after the fact does not in any way reflect poorly on their accurate retelling of the Gospel story.