The Vulgate Bible (382-384 CE) was the inspired true word of God in an incomprehensible Latin, the language of the educated people. The biblical texts appeared in scarce manuscript form in the Middle Ages. Few people had access to read the Bible, because most were illiterate. Most people were content to glean the Bible stories from paintings, stain glass windows, passion plays, and preaching. There was never any question as to its interpretation since the educated Church leaders, who had studied the Bible, pronounced what the correct traditional understanding of the Bible was.
The books of the Bible were formed gradually. They are the product of Jewish and Christian religious communities that was 95% illiterate. These stories were first word of mouth, then later put into writing. Moses did not write all the books of the Pentateuch. Paul did not write all the letters ascribed to him. Matthew and Luke partially rewrote Mark with other sources. There were additions and deletions, but we have what God wanted us to have.