The state space here looks pretty small, it seems to me that with so much training it's just a case of brute-force search. When I think of "tool use" in regards to the intelligence of early humans, I imagine something more like [0] where the state space is enormous and it takes a good deal of reasoning and planning to get to a desired result.
[0] https://www.youtube.com/watch?v=BN-34JfUrHY