My supporting POV on selfishness motivating human moral values

[smax]

I think that it's a big misnoemer to say that 'we' collectively were for slavery or the genocide of the American Indians. There were always dissenters and slavery always had people opposed to it.

I don't think I ever inferred a complete and utter consensus. In fact, because moral values are selfishly rooted, it's naive and mathematically unlikely to think that a complete and utter consensus has every existed. People obviously had selfish reasons for wanting genocide and slavery and others had selfish reasons for opposing it. 

That's really not the point, anyway. The point is, theists often argue that there is inherent moral value which can only be explained by god. But the course of human history clearly demonstrates that no such divine moral value exists. We are individuals (or self), therefore, we are naturally selfish. Are values are based around that nature. That's why killing a spider or an ant or a cockroach is an action that has no significant effect on moral conscience. It does not evidently carry with it consequences for the individual. 

That is typical, of course. But, conversely, I have occasionally run into people who do have a moral conscience about killing certain insects like spiders. For example: I once had a person tell me, "Don't kill Daddy Long Leg Spiders, they kill other spiders and they eat flies." This person developed a moral association with the killing of one particular insect that was obviously rooted in selfish interests. 

I'm sure you know that, in some countries, people consume dogs as food. In the United States, that is generally considered morally appalling. And, why? Because people in the United States find joy in having them as pets. They have also been found to be useful in hunting, police work, and assisting the blind. But in other countries their value is found in the taste they can produce. 

Completely different moral values, both rooted in selfish interests.