The dead sea scrolls are not originals, but they predate Christianity. Not everyone believes Hebrew scriptures are cherished works, then or now.
Yes, documents disentegrate, yet many documents are written on stone, as in Egypt, or fired clay as in Sumeria, and are much older and intact. They wanted them to last, in their original form.
The originals may not have been the best for early Christians, but it may be because the originals did not mesh with their own beliefs, so they altered them accordingly.
Still no historical evidence of Jesus here.