I'm going to give you the benefit of the doubt and assume you aren't a scam, just an over-eager idea guy.
You *can* get "free" work from artists but you NEED a functional game first filled with placeholders first.>But they'll steal my idea!!!!!!
No one's going to steal your idea, ideas aren't unique, the execution of ideas are unique and you've already got x amount of lead time on anyone that would copy you (and they can't copy you 1:1 anyway, so it's irrelevant), EVERY game has clones and competition that's what makes for a genre.
Anyway the important part is YOU NEED A WORKING GAME WITH PLACEHOLDER SHIT, and ideally some sketches or descriptions of the setting and shit.
Once you've got those things, you can entice an amateur / entry level artist to make assets for you (or a medium level artist willing to take a risk for exposure).