When you look at all those various moral guidelines in different traditions all across the world, you will eventually find out that they are all based on impartial observation of nature. That is, they de/prescribe a way of living in the least painful way, which culminates in understanding (or knowledge of) why said way (and thus also the guideline) works. All the while taking into account the toolset of human propensities as well as the causal nature of the universe, that is, objective facts.

So, by denying rights of a certain group you create unnecessary pain, turmoil, etc. Simple as that. And since there are no intrinsic objective values in universe (a grain of sand has the same value as, say, a nugget of gold or human being; "women and minorities" have the same value as "old white men"; etc.), those guidelines mentioned above do not pertain merely to humans.

Thus, e.g. a “parasite-centric moral code” would state, “Don’t take from your host more than is necessary because it will adversely affect your wellbeing.” :D

https://senderspike.medium.com/the-problem-of-evil-569af1681d97

https://senderspike.medium.com/christ-buddha-and-the-new-reformation-92583edd35aa

https://senderspike.medium.com/the-way-of-torah-1fc65d8a36c9