Suppose we grant the premise that human intelligence is doing something over and above computing functions in the Turing sense (I'm personally not convinced that anything in the universe can do that, but that's beside the point). That still doesn't preclude the possibility of artificial intelligence. Why? Because, you can't claim with a straight face that human brains are the only arrangements of matter that physics will grant general intelligence. That would just be too insanely arbitrary. There are a lot of possible arrangements of matter. You would expect, a priori, for a tiny proportion of those arrangements of matter to be smart. But a small fraction of an enormous, combinatorially large number is still combinatorially large.

Note that consciousness isn't necessary or relevant for the purposes of this argument. We only care about what the AI is capable of, whether it's experiencing qualia while it's taking over the world or whatever is immaterial.

Once you grant that there are other possible configurations of matter that could be generally intelligent, the only other thing you have to grant is that humanity will one day be capable of manufacturing some of them. Assuming a wide variety of possible arrangements, it would seem unlikely that there was some fundamental law of the universe that prevented us from manufacturing intelligence.