You don't know how the human brain works. The brain gives us consciousness.

These two things make it extremely special. Probably the most special thing on earth.

Emergent properties are interesting, but it is still just electrical conduction in an electrolyte soup. We have no idea what constructs of matter do or do not have consciousness, it's possible all matter has some form of it. It's entirely possible the brain is utterly unspecial in that regard.

Regardless, we're talking about cognitive thinking and decision making, not consciousness. The two are not dependant on each other.

To be clear, I agree with you. We haven't discovered anything in the brain that a computer couldn't simulate, so there's no reason to believe "thinking" is reserved for humans.