As far as I understand, art is typically understood to have two components: expression and impression. The creation of something, anything, as a form of self-expression, is considered art. Additionally, though, art is in eyes of the beholder. If a feeling is inspired in someone by the observation of a thing, act, etc, then it becomes art to them, in that moment. Notably, though, it doesn't necessarily make that thing art to anyone else, unless it is curated at which point that curation is a form of expression.

These definitions are distinct from the requirements for copyright.