I wonder how they managed to tell a complex story like that before the invention of writing?
The dead sea scrolls are old manuscripts, including several Bible books, but they date after most of those books were written.
The dead sea scrolls date from 3rd century BCE to 1st century CE. At that time, most of the OT had been finalized. The value of the scrolls is that they are hard copies of these books that are a lot older than previous copies we had.