While this is an interesting point, I'd say that this is also true of a human brain.

It’s an assumption, with the LLM it is a fact. There is only one source of entropy, whatever the seed value is to any pseudo random number generator used for stochastic operations. Given those values, everything is deterministic. For the brain, it’s not at all obvious that this is true.

We have the LLM code.

You don't have the brain code.