If you’re going to break it down that far, why stop? Your “self” is not your central nervous system, but a portion of it - and not a very large one. It’s your consciousness. Most of what your nervous system does is not conscious.
Your self (and mine) are but a small portion of a single organ in a large network of organs and tissues and cells and bacteria. We developed because it was advantageous for our bodies - which predate our consciousness - to have pilots. We are periphery. We are a single part of an ecosystem. And definitely not the center of it
It all depends on context, imo. People should generally leave other people’s private property alone. But if it’s an ugly cinderblock wall downtown, some kind of drab piece of infrastructure, and the graffiti artist is actually making an effort to make it look good - it can be public art