alt Hacker NewsWriting might be helpful for intellectuals, but it's certainly not necessary. Socrates has a whole argument about written argumentation being a sign of a weak mind.
Moreover, we have records from some of these precolonial intellectual traditions in the Americas. The nahua genre of huehuetlatolli is an excellent example in many ways. The selectively preserved bits we have resemble something closer to Confucianism than mathematics, but keep in mind we have a narrow selection from a single genre in a much wider landscape.
In what's now US territory, proto-writing systems (emoji are a modern example of these) existed. There were also intellectual traditions associated with them, particularly among southwestern groups like the Puebloans. Those are relatively closed to academics for a variety of historical reasons and consequently understudied, but we know they existed.
So first Socrates had opinions but is certainty not an authority on the development of humanity through time. Also ironically we know what he supposedly said and are still talking about it because his words have been written down.
They have been written down because there was in Athenian society enough surplus/inequality for those guys to hang out and talk and be influencers (while their wives and slaves were doing all the hard work) and produce some kind of paper/parchment.
Just like the Aztec empire (from whom we have the huehuetlatolli) who also had production surplus thus social classes thus the leisure of an intellectual life.
Both have benefited from 10000 years of settled human history painstakingly modifying the landscape to create that surplus and yet they still didn't have algebra so there's no shot this collection of tribes 12000 were conceptualizing the law of large numbers or whatnot.
Maybe I overreacted but I feel like this kind of blurb in article sounds good but is is completely misleading in that it crushes developmental history into a simple narrative to pander to a crowd of people lacking curiosity when it goes beyond knowing that colonialism is bad
So sorry I may have been talking past you to my make point but thank for your substantiated comment, that was interesting information