You just slap a topology on things and you get an effective type theory that gets mostly good results which allow you to elide most of the complexity. This in turn allows you to reason about more complex things at a loss of fidelity — what we call abstraction.
If you think being able to recognize a forest rather than be overwhelmed by the number of leaves on trees is useful, then you understand why humans do that.
Says the person who has uttered a sentence chock full of categories!
The "what" of something is part and parcel of intelligibility. If reality is intelligible, and we are truly rational creatures that are able to know this reality, then this would entail that reality is divided into kinds that we can recognize. What those kinds are, and which things belong to which kinds, is a separate question, indeed the question in this article as it relates to living things.
