related to the complexity of information processing in the substrate

Not directly related. I think it has a lot to do with being roughly isomorphic to how a human thinks, which requires large complexity, but a particular complexity.

When I evaluate such questions IRL, like in the case of helping out an injured bird, or feeding my cat, I notice that my decisions seem to depend on whether I feel empathy for the thing. That is, do my algorithms recognize it as a being, or as a thing.

But then empathy can be hacked or faulty (see for example pictures of african children, cats and small animals, ugly disfigured people, far away people, etc), so I think of a sort of "abstract empathy" that is doing the job of recognizing morally valuable beings without all the bugs of my particular implementation of it.

In other words, I think it's a matter of moral philosophy, not metaphysics.