I think you've distilled it well: I don't believe that human consciousness can be explained.

Obviously, we find neural mechanisms for aspects of it: of cognition, learning, language, movement, etc. And obviously there are the effects of drugs, e.g. anesthesia, psychedelics, anti-anxiety, etc.

But these are all effects on consciousness, they are not an explanation for the very existence of the observer, so to speak. And I don't believe that can be touched rigorously. The best we'll ever be able to do is gesture at it broadly and say "well, it certainly seems like everything has a physical cause and explanation." Whereas I take a different view: it certainly seems as though there is something special about consciousness.

It is certainly of the universe, and obviously interacts with the physical. But it also seems to go beyond it. The experience itself exists. And I do believe that this is intuitively obvious - we know we exist, we know we have a type of free will (obviously imperfect, affected by various circumstances, but nevertheless we exist).

But because we want to feel that everything has an explanation, and physical science has been so powerful and effective in every other domain, there's a tendency to say - "well, that stuff must be an illusion. Human perception is fallible."