Consider: the Library of Congress has (literally) a copy of every work that has ever been in print in the U.S. The Internet Archive has archived much of the public internet. There are other resources like arXiv, Zenodo, etc. Many of these organizations are very conscientious about data retention and longevity.
Is there even more data that could be saved in principle? Of course. But the amount of data we're talking about is already so much dramatically larger than what we have about, say, the antiquities, that it seems like an absurd comparison. The problem in the future (excluding extinction-level events) will be wading through that data, which even in the handful of resources I've mentioned above will be so far beyond any single human's ability to understand that it's just unfathomable.