Seeing them put together in an animation like that exposes quite an oddity: if the animation is meant to look like breathing, then they are moving from a particularly strange (and inconsistent across the angles) position. For example, when the zombieman inhales, not only does his chest rise as you might expect, but so does the top half of his ass.
During breathing, the chest usually moves upwards and outwards slightly as you inhale, and that
might also shift the shoulders and maybe the arms a little too, but that's about it. In fact, if it's just resting breathing, it's really only the diaphragm that is moving and the chest doesn't even move much. It would be very strange for the whole upper half of the body (especially from half-way up the ass) to shift up in this way. Of course, zombie physiology could be different.

(and, yes, I understand about the limitations of having so few pixels to play with etc.)