This is a ludicrous reduction of the point McKenna was making. You're acting like he didn't directly address this fallacy. Go read The Invisible Landscape, listen to one of the lectures that covers this material (such as Eros and the Eschaton and / or his address to the Jung Society), and then address the whole of what he was saying.
If you don't think that human neurochemistry is astonishing, I think that's weird. But don't sit here and straw man his research; that doesn't help anyone.
Neurochemistry and the experience of consciousness are very astonishing, I just think it's a bit egocentric to assume they're the most astonishing things in the universe.
Nobody said they were the "most astonishing things in the universe" - I'm not sure where you get this stuff. It's another straw man.
McKenna says that neurochemistry, and its material application called "the psychedelic experience," is the most astonishing thing you can personally suppose, or in some cases, even that you can't suppose. But that doesn't say anything about the (real or imagined) notion of a totality of "things in the universe."
If you don't think that human neurochemistry is astonishing, I think that's weird. But don't sit here and straw man his research; that doesn't help anyone.