Everyone from Aristotle to Horace to Edmund Burke to Tolstoy to Adorno has had their say on "What is Art?" and "Who Is an Artist?. So I recognize there is quite a lot to say about the subject, and it would be hopeless to cover the subject here in any meaningful way. I am basically just voicing objections to what I consider slack or easy ways to talk about art. For example, I don't think just because something or someone is "warm-hearted" that that makes it art, admirable as that might be as a social sentiment. Ditto concern for the audience, uplift, social good, patriotism, etc. Art may be none of things and still be great art. I suppose I'm a Modernist by inclination, and say that art is for itself.
As for the artist, that label is slapped on a lot of folks, but time sifts the pretenders out and eventually we see who matters more clearly. I'm not arguing for the great man (or great woman) theory of art as Bev suggests, which posits that great men (it's a sexist perspective usually) move history in certain ways. I posited the idea of the great artist as an aesthetic construct rather than an historical vehicle. Again, I take a Modernist view that importance is not in social effect, but in the art itself.
This is actually an old-fashioned position now, as post-modernism seeks to erase the concept of the single, creating artist. That just does not accord with my understanding and apprehension of art: music, literature, painting. Artists can be influenced by a 1000 things, as we all are, but we all have not written "Ulysses," or painted "Number 8, 1949," or composed "Le Sacre du Printemps."