Humans began to rapidly accumulate technological knowledge 600k years ago

I personally believe forms of writing and record keeping are far, far older than we think, having been discovered and forgotten repeatedly. Very hard for something hundreds of thousands of years old to be preserved. Once you can pass on information orally and written through the generations, knowledge will always improve.

Record keeping doesn't need writing. Like Incas with their knotted ropes (probably not how how you call it in English).

Also, while some central Asians could read and write (they had courrier relay to deliver letters), their administrative/taxing/military system, the decimal system, worked without any writing for two thousand years, only by making a mark on a wooden branch for each person in an Arban, a mark on another for each Arban, again for each Ja'un, again for each minggan. That's how they counted and this was taught without text for at least 1500 years (Mongols wrote something about it in the 13th century, but this system is at least from 300BCE and the Xiongnus)