Well, it's anti-metaphysical philosophy, so we're talking positivism which is the classic example of scientism.
Whatever it is, you're assuming we should be as rational as possible. That rationalism is indeed philosophical and nonrational (not itself justified by reason, without begging the question). Metaphysics and theology enter the picture because at some level we prefer nonrational, emotionally satisfying, creative, or socially useful explanations.
But you also seem to be describing the situation rather than prescribing it. You're saying we evolved to prefer plus sum outcomes, so we praise those by positing human rights on their basis. That's not yet to say the outcomes of such natural selection are good (unless you're committing the naturalistic fallacy). Instead, you're explaining why we think of them as good. We should be careful to distinguish between explanations and arguments, and between descriptions and prescriptions.
My point about the freeloaders is that you'd be in danger of making values subjective were it not for your point about the need for productivity or economic growth.
In any case, I don't see how we evolved to prefer the growth that makes plus sum outcomes possible in large societies. Rather, we evolved to prefer the stability of Stone Age nomadic, hunter-gatherer life. Yes, those groups were egalitarian, so all the members got what they needed, but that was because the impact of the small groups was negligible compared to the scale of what the environment could provide. There was little problem of scarcity in the Stone Age because the small groups could always move to where there was better food and shelter, and abundant nature provided. Everyone got to win in the Stone Age not so much because of social rules, but because the natural resources vastly outweighed the human impact.
The progressive idea of economic growth comes from civilization which runs counter to our evolved hardwiring. In cities and kingdoms, we begin to take more from nature than it can provide, so how we organize our groups starts to determine how we survive. We survive under these new conditions not because of evolution, but because of social games we invent such as the theocratic or capitalistic frauds (or so-called nobles lies). The latter fraud holds out the possibility of infinite economic growth, which is meant to justify the enormous inequality that occurs even in capitalism which was supposed to have decentralized political power. It's a bait-and-switch ruse.
The societies that grow and have more and more goods to distribute are typically based as much on fraud and irrational myth as on honest cooperation and negotiation. The parasites and predators at the top have to convince the masses to settle for the crumbs that fall from the high table (something like the trickle-down theory).
My point, then, would be that if some such predatory frauds are necessary for economic growth and for plus sum outcomes in the civilized (non-evolutionary) context, your description/explanation of events would have to register that fact and not pretend as though it's consistent with our ethical principles. Economics would clash with morality since morality would have us repudiate the psychopaths in charge of those mass frauds and economic inequality.
A test for when we'd be done with self-exploration would be whether we're inclined to destroy ourselves or to live in a sustainable way. Similarly, you don't let someone out of the madhouse if they're suicidal. Alas, the fixation on "plus sum outcomes" even in civilizational history--when we've left behind our genetic behavioural constraints and our Stone Age conservatism-- requires economic growth, which is arguably unsustainable (and part of an immoral fraud that provides excuses for predation-based inequality).
