I would semi agree with your no printing presses point if it weren't for the dead sea scrolls. The Dead Sea Scrolls contained the oldest known copies of the Septuagint which is the Greek translation of the old testament. They were %99.9 the same as the oldest known copies we had of the Septuagint at the time of discovery (1948 I believe) and the differences were mainly spelling. This is also important because the Hebrew Masoretic text was created from earlier Hebrew source texts sometime before the 11th century AD but there were VERY many more intentional changes in them than the differences between the two Septuagint copies that i mentioned before. The changes were mainly in dates and genealogies so obviously the anti Jesus Jews were trying to change key Genealogies to try and disprove Jesus's lineage and sabotage Christianity. Ironically most modern English bible translations use the Masoretic text -_- ....by the way the book of Enoch in its entirety was found within the Dead Sea Scrolls.....also the Ethiopian orthodox Church was the only sect of Christianity that we know of that used the book of Enoch traditionally in their biblical texts.