All of it is stiff
none of the movemts feel like something moving, it looks like things being moved
the run needs more frames, since it's both too fast and it doesn't show any of the actually essential frames of a run, which are actually the frames inbetween the main frames that bring the whole thing together. Also, the way he just suddenly comes to a halt upright is super awkward, even if you did add that slide at the end. Keep in mind that when you do things, your entire body moves even if only slightly, so there really should never be a moment when someone has momentum while being and remaining completely still