Ethics are very often framed around humans. Utilitarianism focuses on human happiness. Kant talks about never using humans as tools, which he states is an equivalent formulation of his categorical imperative. These two alone probably make up the two most famous ethical theories.
Why is this so? Why is the notion of humans so central to the notion of ethics? Surely ethics has an independent existence of humanity? If I was the only human in this world with only myself, my thoughts, my actions, animals, and nature, then surely, in such a world, it would still be possible for me act morally.
It becomes even less intuitive when one considers that while humans can be a source of good, they can also be a source of evil. So why define morality based on how it affects humans, when humans themselves can be a force of immorality?
To sum it up, my question is, why are moral actions so often defined around humans, when morality (intuitively) exists independent of humans and when humans (sometimes) are immoral actors themselves?