At some level of abstraction, sure. Brain is computer. But it's not an LLM. And it's not a CPU. The brain is a bunch of parts that integrate a constant stream of sensory input and the parts do a bunch of things that add up to a bunch of outputs. I guess there's some language stuff in there, but that's not the whole story at all, and it's not, AFAICT, predictive. And it also doesn't include all the stuff that happens outside the brain. Or in other systems.

So yeah: brain is computer. That's not entirely false. Just not sure how useful it is as an observation.