Wiki answers says; "Of course we do not know. The first 'artists' painted animals and sign on cave walls. They may of course be called pre-historic. Before the 12th century painters did not sign their work they were considered workers like carpenters or bricklayers. All this means that we do not know who we might call the first."
I know! I know!(waving my hand in the air frantically) The first real artist is God.