I see. For sooner it's a really great work! ))
Yes, of course, in here we may to devote oneself to perfectionism, but in real we not have time for this, sometimes.

Maybe you think in this direction? I donn't know which breed you try to paint...

Work more on his head know...

Great work! 
But this need some correction, in my opinion.

See on his legs, you forget about form of calf on his leg. Ir's look strange. I quick edit you characters, see it maybe this help you.
Man - fix legs and shoulder (In my opinion he is the best from other  ). Girl - Right hand is too long.  Legs not on surface and proportions of thigh and calf is wrong. It's just edit you may do this more better.


And this too trouble with legs (look like a hose) and trouble with his left hand - she is very small and strange position.


There just legs

The broken extremity very distinctly on your animation for each person.

And a bit comment.  This kick is not to do with heel, because this is may broke you achilles' sinew and will be a invalid for all live )) For this kick striking surface is footstep with a bit elongate toe.
Anyway you do a good job.

Me very like this work, therefore I am to permit myself some change in you work  Color, form on face and hand, position hand. Maybe is not enough, but you may do this better!
Just see on animation - what I what talk to you.

And maybe change bg? Something like this:

Maybe this color is not what you want, but I  mean - if light is warm, the shadow is cold and the reverse this.
If you want you may use this edit as you wish.
I want see the final.

NICE!!! )) I know it's sketch, But think about his ear, maybe more point on age and fix form. Also form face - maybe left in more shadow? And form in left cheek-bone not as in right. And eyes more AA - replace yellow on white. Something like this ))
Please, don't stop!