It's a neat idea for sure, but the out of place artifacts are rarely/never as mysterious as people like Graham Hancock would suggest.

Younger Dryas wasn't as catastrophic either. Nor are flood myths as unified.

It's fun to imagine possibilities like that but I can't conceive of how a society could advance to a nonphysical/digital technology paradigm without impacting the earth in enormously detectable ways.

I think it's interesting to imagine a scenario like what if European explorers shipwrecked on a place like Rapa Nui, the most isolated inhabitable place on the planet. How many generations could they maintain knowledge of the globe, and their culture.

Obviously the Polynesians basically maintained their language (ie it was identifiable as a polynesian dialect) for ~500+ years in plausibly total isolation.