This.. bird is an animal but now we add air planes. It too flies. Is bird an animal or flying object? Already problems. Reusability was biggest reason I liked

This.. bird is an animal but now we add air planes. It too flies. Is bird an animal or flying object? Already problems. Reusability was biggest reason I liked oop. But you can't do that if while world doesn't cleanly derives from singularity. it gets screwy fast if world changes.