So the answer (mostly verbatim) I gave my minion off the top of my head was that art is something that in my view is one big thing that separates us from the rest of the animal kingdom. Humans are the only species (as far as I am aware) that create art. It's to do with the sheer luxury of creating for creation's sake - something that explores the extravagance we can afford with our lifestyles that are above that of the other animals - it's not all or even mainly about survival for us.
It ties into ancient Greek philosophy. The ancient Greeks mused on the purpose of life, and their answer was that they wanted to leave their mark on the world, through stories of glory, through building monuments, through leaving a legacy in terms of buildings, technology, aesthetics, science, etcetera. Art is human kind's expression that we are unique. Art is one important (in my view possibly the most important) special difference and that through expressing it, we are closer to the core of what it is to be human.
Taken a drink of something recently? I just realised I hold my elbow up level with my face now by default. Argh. ;)