You chose a really tough perspective, not only is it really hard to actually animate from it, to actually show different enough silouette to show movement makes it even harder. Since nothing is impossible I tried doing a redesign + running animation.
Pay attention to anatomy. A human body isn't just a large rectangle. His right arm also has a weird shoulder lump, that has no reason to exist. I see you had a hard time with his feet and legs, legs are actually half of the human body so they are pretty long. You could make them shorter, but then you have to make them thin as well.
When running/walking what you are pretty much doing is swinging your limbs back and forth. This means that in your animation when you have 3 frames of the left leg swinging forwards, you will have 3 frames of the left leg swinging backwards. In your animation you have 3 frames of the right leg in front of the body and 1 behind it. This makes it look like he is limping, since he spends so little time on his left leg. The left leg actually does get 2 frames in front and 2 frames behind, but you have 1 frame where it shoots out in front of the body, which is very unnatural. Try making the walking movement with your own body and see how your legs fold and move.
Mostly i would recommend choosing an easier perspective, either from the front or from the side, doing different perspectives is pretty hard, especially if you are just beginning.