I see all parts of the universe as being products of interactions between smaller parts, which interact with each other as well as with external aspects of the universe.
If external aspects to the universe means something beyond this universe, then I don't know what that could be.
I didn't mean it like that. What I mean is that a human or a planet, for example, consists of smaller constituents parts, such as organs and tissues in the case of the human; or oceans, forests, deserts, lakes, mountains, the mantle, magnetic field, atmosphere, etc. for the Earth.
Then what I'm saying is that the constituent parts of any entity don't just interact with each other, e.g. your liver with your blood stream and your blood with your heart, etc. but there is also interaction between various parts and various aspects of the external universe, e.g. a forest interacts with the sun by absorbing/reflecting light, but also with humans, who use it in various ways.
So (parts of) the sun are interacting with (parts of) a forest, which are interacting with, say, your liver by producing compounds that you ingest in one way or other, which end up interacting with your liver cells.
I'm glad you agreed with me about taxonomies, etc; so hopefully you can easily see what I mean about parts of wholes interacting with parts of other wholes without the wholes necessarily behaving as gatekeepers, although there are of course borders/gatekeeping that happens at various levels, such as the skin, cell-membranes, orifices that let substances enter and exit the body, etc.
So it's not like the Earth interacts with the sun while the constituent parts of Earth only interact with each other. Parts of each interact with each other's parts, but also as wholes, and also as wholes interacting with parts of other wholes, etc.
So there is a lot of interaction involved in causation, and so things can't just be determined by internal causal factors. What's more, just because many causal factors interact to determine individual agency, that doesn't mean that there isn't autonomous decision-making going on at various levels of interacting networks of causal factors.