Using your term, we didn't 'know' how gravity worked even after Newton's and Kepler's work, still we were able to construct accurate ballistics, because we still knew something.
That example is not congruent with the AI claims made here.
First, we still do not know how gravity works. We have observed its effects and have drawn conclusions that were then formulated into physical "laws", but nobody understands the mechanisms of gravity.
Second, gravity is a very simple process compared with the processes of intelligent thought. We don't even know that thought occurs in the brain. The brain might just be an I/O interface to a completely different repository of intellect that we haven't discovered yet (e.g., what some people call the soul). Maybe, maybe not. We just don't know. Nobody has proven that intelligence resides in the brain. We've only poked at it and observed effects.
Given that level of uncertainty, nobody currently understands neurons and their role in intelligence to do anything more than wild, unprovable guesses.