Yeah I don't think it's a broad claim about human uniqueness to say that 1 the brain seems to be important for being conscious 2 the brain is very complicated and there's a lot going on there that we don't understand

I don't even need to assert 2, really. There are substantial and deeply integrated parts of the brain -- the modulatory neurotransmitters, the hippocampus and parahippocampal areas, the TPJ and other areas important for theory of mind etc -- that simply don't exist in LLMs