practice makes perfect.
I'm still new to animating myself. Though I've seen enough beginner animations to say you got a ways to go. I wont be so harsh on rating though since I know its your first. But I still have to be honest and give you a low score.
I'll never understand pixel animation, much less make it. So I'll say this; work on speed variations and fluency. Add some sound, and a default preloader, and perhaps make the animation a bit longer. Then you should at least have a decent score to get by with. Right now it looks too GIFy because of all that. Good luck to you.