The Maya are still around, but the Maya civilization's institutions were all destroyed. And the Spanish made a point of seeking out all the Maya books [1] they could find and burning them. So a lot of knowledge was lost.
The link doesn't mention "seeking out" those books, in fact it mentions catholic priests both burning and lamenting the burn.
For this reason, one of the most fascinating historical relics to me are the Incan Quipu [0]. Not only because their logic appears to be 'proto-computational' (at the very least a very complex system of encoding numeric and narrative information through sequences of knots that were also used directly for calculations), but since, neither in the form of a valuable material like gold nor obviously a book to be destroyed, a large enough number survived to this day. There are few traces of the past we know exist that might contain everything from astronomical calculations to old social-institutional histories.
They're comparable in that sense to the Heculaneum manuscripts, which researchers have lately made great progress on with deep learning [1]. I hope an equivalent initiative someday starts on the Quipu.
[0] https://en.wikipedia.org/wiki/Quipu [1] https://www2.cs.uky.edu/dri/herculaneum-papyrus-scrolls/