They survive because someone cared enough about it to make a copy.
Sometimes, and sometimes we have the originals. And to make a copy, you need an original, and sometimes the copies were made >100 years after the original.
Burrowing stuff sometimes works, however, a lot is lost. Even when we attempt to save things, it often doesn't work.
So let's not even try, much less try to solve this reliability problem.
A lot of the classics we have today are copies of copies of copies. The Dead sea scrolls are the oldest known copy of the bible, and nobody believes they are originals. They are mostly interesting because they can help us track down where copies made a mistake and so the text we consider original today might be wrong. (but we don't know - there is also the possibility those scrolls were put hidden because when checking the copy they found mistakes and so put them where they wouldn't be used - not wanting to destroy the parts that were God's word)
Comments
Sometimes, and sometimes we have the originals. And to make a copy, you need an original, and sometimes the copies were made >100 years after the original.
So let's not even try, much less try to solve this reliability problem.
A lot of the classics we have today are copies of copies of copies. The Dead sea scrolls are the oldest known copy of the bible, and nobody believes they are originals. They are mostly interesting because they can help us track down where copies made a mistake and so the text we consider original today might be wrong. (but we don't know - there is also the possibility those scrolls were put hidden because when checking the copy they found mistakes and so put them where they wouldn't be used - not wanting to destroy the parts that were God's word)