I think we are basically self-centered because that’s just how nature made us. But having said that, being an outcast and a loner is dangerous, and so we naturally seek out a social network as a support group. Self-centered cannot always be just about me.
I’m not too big on academic thinking and it seems smart to just accept that our more instinctive and emotional sides are buried deep in the body-and-brain’s functioning in manners very poorly understood. This means it is potentially foolish to insist that everything proven by science is correct and everything else is nonsense. At some point you can go with gut feelings — even if that is useless for getting qualifications. (As a side issue here, you can see the authoritarian nature of formal education in that only approved knowledge is given credence. And let’s not forget that approved knowledge refused for centuries to accept Earth was not the center of the universe.)
The problem with the empiricists is that they tend to reduce everything to whatever is seen in the science lab, whereas many of the rest have fanciful notions of gods instructing them about moral righteousness. Both these schools are promoting their agendas — be they science or religion.
The trolley problem you mention makes sense once you allow for our distance from other people. Where we make decisions without having to see the white of the other’s eye, so to speak, it is easy to be cool and calculating. Entire armies have been marshaled into war on that basis, whereas we are generally averse to injuring anyone we are in close contact with. It’s that social group thing again — likely linked to mirror neurons.
Animals are behaving according to their instinct, yet immoral acts are common among species…
I think morality is a manmade concept and little else. For the most part the animal kingdom only kills to defend, protect, and for food. Humans on the other hand will butcher their own kind in the millions because they are paranoid or have been told to do their moral duty… or some such shit. We are quite different from other species in this respect.
Because ultimately animals have no free-will they act according to their instinct, therefore these immoral acts must be programmed in them.
The issue of freewill versus determinism is so big, I can only suggest you do not write as if it is a resolved question. And also as I say, judging acts as immoral is a uniquely human habit — and not even one we can agree on as you point out.