This you can count as a good evidence:

Only 32 different symbols have been in historical caves worldwide. No more variations, which suggests them being a standard writing system. The oldest findings backs to 40,000 years ago. And literally worldwide; they have been found in all continents.

https://www.openculture.com/2025/09/40000-year-old-symbols-found-in-caves-worldwide-may-be-the-earliest-written-language.html

@openculture