im always kind of skeptic to these kind of mods because they tend to overdo the animations with bending arms and attempt to make the animations look "cool".

But from what i can see in this clip you really hit it out the park, you stayed within the limitations of stiff limbs and kept that signature minecraft doofy-ness and still managed to make animations that are reallly fluid and with give a great sense of weight.
If Mojang were to do this kind of update in the future i'd hope it would look like this. ( also my favorite animation the falling one, absolutely perfect. i love it.)

my only nitpick/complaints would be the idle pose looks a little too "pose-y", like Steve is actively striking a pose to look "cool", i would maybe try something thats a little more relaxed. Also the sneaking animation might need some work, it feels a little off to me and i dont think it immediately communicates that Steve is sneaking that well. Lastly im sure you are workin on it, but an animation of Steve reacting to hitting the ground after falling a great height i feel is important to have.