Training takes many years though.

Training took hundreds of thousands of years. Everyone just gets a foundation model to fine tune for another couple of decades before it can start flipping burgers.

It's been something like half a billion years since the first brain.

That was a much smaller model, couldn't do much more than crawl around and run away.

It was still used as part of pretraining the current model.

Nonsense, the current model is a new architectural approach.

It was all explained in that recent paper, "Attention is all your meat"