It's hard to critique animation without seeing it in motion, and it's hard to critique the still frames when there is no spacing between them.
2.5D is not a perspective. It simply refers to a 3D effect achieved with 2D, such as isometric art, art using parallax scrolling, etc. I'm guessing you mean a 3/4 RPG perspective, based on the sprites?
I think all the views could use a bit more hair/top-head to convey the RPG view, if that's what you're going for. The bodies look good but the heads feel rather front/side-on. Perhaps going with a one-pixel eye like on the 4th from the left, top row sprite would work better, it feels much more like they're viewed from above (though I'd still have less forehead and more hair, or if the hair is meant to be receding, emphasise that more).
The feet in the bottom right sprite are a bit much, looks like the character is standing on their feels. The others have more reasonable feet for RPG view.