While I'm rather new to the forum, I think I'm decent at animation and I'd like to be helpful.
So, from what I see, you should exaggerate the movement of the character more - build up anticipation then ease out of movements. Motion isn't uniform, and the speed of any movement is rarely equally quick through out.
Here's how I'd go about improving your animation, step by step.
But first thing's first, I personally think that animating both run cycle sides is tedious and might look janky. Don't draw out the front and back already, draw the for, the silhouette of the character, it's a lot easier to keep track of the characters motions and inconsistencies.
So, I colored it all one color, and removed 6 out of 11 frames, so it's now a 5 frame loop, without a distinguishable front/ back side of the character. The little pip under the foot just helps me understand the motion a lot better and judge the best way to loop.
Next, I added motion to the character as a whole. The body doesn't stay at the same height when moving, it oscillates up and down, as well as diagonally. Think of running as jumps in succession, which, in a way, it is. I also started to fiddle with the arms, as now it's apparent that the are stiff - staying at the same spot for too long and keeping the same pose unnaturally.
Added flow to the limbs - I guess you could say that the farther something is out on a limb, the more they are affected by inertia. Hands are flexible things, for an example, your palm doesn't start moving the moment your biceps raise your hand, unless you're tensing up your whole hand.
Only now do should you think about sides - orange being in front. I didn't really do a lot here, just edited a little bit around so there'd be frames where the hand transitions smoothly throughout the swings. Also, edit, I doubled the frame count before coloring the orange.
Hopefully this was at least slightly helpful, and maybe this can help you as a reference. Also, I really suggest watching https://vimeo.com/93206523
, which is really helpful and outlines basic principles of animation and motion.