Please remove the black text. Black is not in the palette.
I'm not seeing the moai likeness very much here. If I didn't already know.. Well, I wouldn't know just by looking at the picture that any of those were supposed to be moai, or moai-influenced.
I think, if you're beginning pixel art, you should start out simple, don't overcomplicate things by trying to do something you obviously aren't capable of doing decently yet. Yes, challenge yourself frequently by restricting yourself via color or size, etc. but within reasonable bounds. Also, frequently post any of your results on a pixel/drawing forum for critique. I know Metaru already gave you some crits on this piece, but it doesn't look like you took them. If you want to get better, take the steps to do so.
If you're new to drawing, I'd recommend you start off with another medium, such as pencil/paper. Pixels don't lend themselves well to beginners. And here in PJ, quite frankly I wouldn't submit anything you're not proud of, or that you know sucks. But keep it somewhere anyway, and don't delete it, so you can see your progress. It always helps me looking at crappier, previous drawings, to see how far I've come, and that I can only good better.
sorry, i fix the preview.
Thx Dr, i keep that on mind