Apart from the Ethiopian, whom Philip meets Acts 8;29, is there any evidence for the private ownership of any works of Scripture before about 400 A.D.? Otherwise, what is the earliest evidence that anyone has heard of?
According to Luke, in the book of Acts, the members of the church in Berea seem to have possessed ownership of the scriptures since he records:
These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so
Acts 17:11 KJV
The very rudimentary - though highly expressive - language of the book of Job, and its basic yet imaginative content lead me to suspect that Moses translated it from (perhaps) cuneiform into Hebrew when either he was in Midian for forty years or when he was in the desert for forty years.
If it is the case that Jethro the priest, in Midian, Moses' father in law, was a 'priest' - whatever that meant at the time prior to Levitical priesthood - then his priesthood may have been a feature of his possessing the book of Job.
Either he was a priest because he possessed it or he possessed it because he was a 'priest'.
Given Job's longevity and given various clues in the book, Job would have been contemporary with Abraham's grandfather. Thus the book of Job, written either by Job himself, or, more likely, by Elihu, would be the oldest known - coherent - writing on earth.
All other artefacts, which can be sensibly dated, are around 2,000 to 2,500 BC. The book of Job is by far the most extensive book, from any source upon earth, from that period.
I suggest that Elihu wrote the book; Jethro inherited it; and Moses translated it into Hebrew.