It isn't necessary that "this AI [have capabilities] that a human can never have". The issue is how those capabilities (possibly shared, possibly not shared be

It isn't necessary that "this AI [have capabilities] that a human can never have". The issue is how those capabilities (possibly shared, possibly not shared between some humans and AI) are deployed and to what ends. There's also a speed question. Maybe AI will never be able to do things human cannot, but it seems likely that for the sorts of things most AI-excited folk are excited about, it will be faster than a human most of the time.