It's really easy to say that you're not an artist. An artist is someone we think of as this special breed of creative - they make things based on their inspiration that serves to communicate on it's own. That form of communication stands alone and has it's own aesthetic that "experts" have been trying to categorize and quantify for years - but really, in the end, an artist is a creative that just got lucky. Someone somewhere saw what the creative was doing, heard what they were communicating and decided to promote it.... or even, sometimes, the creative found ways to just promote their work themselves until they found their audience.
Check out Thierry Guetta (aka Mr. Brainwash) - he's a guy that met a bunch of street artists and then decided to be one, sunk a shit ton of money into it, hired a bunch of kids to help him do it and made his fame (check out Exit Through the Gift Shop). It was an unconventional approach but It worked.
As far as I can tell, the thing that really makes an artist is a sincere and lasting choice to do it. It's the same as a commitment to a relationship - you have to do it every day and sometimes that takes a LOT of help, but always that choice has to come from the heart.