I'm not saying the brain IS just an LLM.
I'm saying despite the brains different structure, mechanism, physics and so on ... we can clearly build other mechanics with enough parallels that we can say with some confidence that _we_ can emerge intelligence of different but comparable types, from small components on a scale of billions.
At whichever scale you look, everything boils down to interconnected discrete simple units, even the brain, with an emergent complexity from the interconnections.