This assumes we've been comprehensive in unearthing ancient structures that were buried under water and dirt 10K years ago. We mostly find these types of sites when doing new construction. There is likely countless underground ancient structures undiscovered off the coastline, since sea levels rose more than 120 meters at the end of the last glacial period.

Also, I wouldn't assume at all that knowledge would transfer outside of a localized area. It didn't happen like that in the so-called hearths of civilization like Babylon, Egypt, China, etc.