Andre’, natural selection favors the survival and “flourishing” (meaning, ability to reproduce) of individuals, not species. (It’s a common misconception of evolutionary theory that it is about species rather than individuals.)

I agree that there is more to human ethics than this. Namely, because of cultural evolution, we conceive of flourishing as much broader than just reproduction.

But ethics is still constrained by biology. We want / need certain things and wish to stay away from others because we are a particular kind of social intelligent organism. There are certain things that are objectively good for us and others objectively bad.

Another way to put it is that ethics is about developing and preserving mental / spiritual health, like medicine is about developing and preserving physical health.