May the iterative loop of adding new axes to evaluate on be a natural, healthy progression, instead of needing to frame it as an us-them problem?

If you value humans intrinsically, this is necessarily the loop that will converge. I don't think humans have deep intensional a priori knowledge of the structure of reality. If we did, then we wouldn't need tools like AI because we'd be a superset of that. We can only observe and judge.

If we don't value humans, then sure, I think AI is at the point where it can kill all humans (conditional on sentience and resources etc). Two ways to solve a problem - solve the problem, or eliminate the problem statement. Plenty of easier vectors to eliminate the "problem statement", than say, try to solve problems such as making human life better. If you do value the latter though, there will necessarily be human judgers. That's how it works.