You have relegated the most salient -- but incorrect -- point to a parenthetical remark:

"(The discovery of language systems among birds, whales, porpoises, and other higher life forms has already demoted the uniqueness of our brain.)"

As Descarte said. "I think, therefore I am." Note that he was doing his thinking in words, grammar, i.e., real language. As far as we know, our language is much more capable (i.e., has a greater capacity) than any of the other animal "languages". (Although, it would be great to learn we have underestimated, say, the dolphin.)

If you want to know the origin of consciousness, figure out the origin of language. Consciousness emerges within each maturing individual as they master the local variant of Chomsky's innate grammar. If you want an AI (we can relate to), figure out the foundations of human language. Although that does not rule out an AI that is even more conscious than us because its language is superior. We are nowhere close, yet.