The odd thing is that bad texts are usually the oldest ones found, but the best texts are usually the ones copied. Scrolls scrub themselves as they are rolled and unrolled, and so a constant effort is needed to keep the good texts in use. Bad texts tend to be written by ‘novices’ and then set aside, not used, and can be very old. Example of a bad text might be the Gospel of Peter round last century. An example of a good text saved might be the dead sea scrolls, which were probably good texts that were hidden from the Romans.
I think the most fascinating aspect of the Dead Sea Scrolls is that they substantiate the text of the Septuagint where it diverges from the Massoretic Text.
A key example of how the Septuagint is linked to the New Testament is the issue of the virgin birth because the Septuagint translates Isaiah’s prophecy as parthenos or “virgin” rather than young woman as in the Massoretic text.
That was a key reason the Palestinian Jews banned it and changed the wording of their editions of the Old Testament.