30+ millennia is a long time to be stuck in a rut*. What changed that turned us from stone knives and bear skins into modern technologists, and when? Was it writing? Metals? Food?
*If they answer is “the wheel” then I will appreciate the irony of the phrase “stuck in a [wheel] rut”!
Education, writing, and materials would be independent of agriculture or any one local invention.
It often takes an incredible number of different materials fabricated in uncountable ways for generations before even one single new material can be identified or developed.
Same with inventions.
Each culture that responds to their environment sustainably for millennia is not in a rut compared to those who truly got stuck in some unsustainable way and are no longer with us.
Intercommunication between these different environments can combine the accumulations of education, writing, materials, and inventions, and they can be seen to grow in an exponential way, so it appears those millennia were just the low-slope early part of the same curve.
Lots about the stones; not much about why 'Homo Sapiens'. Is it just because these tools are attributed to Homo Sapiens? I skimmed the article but didn't see anything about human remains or dna analysis.
The whole paper is about microliths, which are only known to be associated with anatomically modern humans (AMH, aka us). This is just "general background knowledge" in the field, so they don't spend any time explaining or analyzing it in the paper.
The particular typology they use here (shea's modes) is also more complicated on this point than the traditional clark framework where you can just say "mode 5 == AMH".
There's a ton of archaeological research into human-made stone tools, worldwide. There's very high degree of confidence at this point into which artifacts can only really be human-made, versus made by other animals or natural processes. My guess is organic evidence of human activity would be really unlikely to survive in the South Asian rainforests, so I'm guessing this one of our better sources of information on human activity there.
If you're asking how do we know this refers to Homo Sapiens, versus other species in the genus Homo, I'm guessing we can't really tell that.
*If they answer is “the wheel” then I will appreciate the irony of the phrase “stuck in a [wheel] rut”!