Humans began to rapidly accumulate technological knowledge 600k years ago

You have to think that there were breakthroughs in communication technology — not just language in general but possibly also one individual who happened to be good at explaining things, either before or after language, who both taught more people, but also taught them how to teach — that led to step changes in technology.

Theory: there are no humans without language. Consider: what language do you think in?

Quite a lot of humans don't think in language, or do only some of the time, see e.g. https://www.iflscience.com/people-with-no-internal-monologue..., https://www.livescience.com/does-everyone-have-inner-monolog..., https://www.bustle.com/wellness/does-everyone-have-an-intern....

There are also humans who can’t conjure up an image in their head. Mozilla cofounder wrote a fairly famous piece about his own experience.

https://www.theverge.com/2016/4/25/11501230/blake-ross-cant-...

If there are people who can’t picture and people who don’t have an inner dialogue, I think it lends more credence to the idea that we don’t have free will and are just a bunch of chemicals controlling our behavior. It also makes you think about consciousness and whether it’s even real.

What even is "free will"? It's an idea that falls apart on close inspection.

You think "I will wash the dishes". You wash the dishes. Ta-daa, free will!

A paralyzed person thinks "I will raise my hand". Nothing happens. No free will!

An ADHD person says to themself "I will wash the dishes". They don't get washed. A different part is broken than to the paralyzed person, but the result is the same.

A lazy person says to their roommate "I refuse to wash the dishes". Free will? They "could", if they were not lazy. Just as the ADHD person "could" if they did not have executive dysfunction. Just as the paralyzed person "could" if their spinal cord were intact.

"Free will", as a philosophical construct, is nothing more than an attempt by the ego to regain a sense of control in the face of the irrefutable realization that the universe is governed by rigid laws, and we are made of universe. (And no, quantum randomness doesn't help you - a random choice is hardly more of an extension of will than a deterministic one).

I agree with the only caveat that the universe should have a maximum amount of precision it uses to calculate every next frame, and at the margin of error of these calculations, non-determinism may arise.

Even if those assumptions were true (and why should they be? the universe is not a computer, does not have "frames") what would that have to do with "free will"?

Why should yours? It seemed like you liked musing about this topic so I added a bit.

You (and I) have no idea if the universe is or not a computer. If you don't see the connection of free will to error margin of a deterministic system then I'm not sure how else to put it. Just imagine a deterministic program getting a bit flipped by a cosmic ray and turning non deterministic and apply that to the universe's system of laws.