> What is more likely in 1000 years to still exist and being readable. The papers caught in some lost ruins or some form of storage media?

The storage media. We have evidence to support this:

* original paper works from 1000 years ago are insanely rare

* more recent storage media provide much more content

How many digital copies of Beowulf do we have? Millions?

How many paper copies from 1000 years ago? one

how many other works from 1000 years ago do we have zero copies of thanks to paper's fragility and thus don't even know existed? probably a lot