Ten-year-old boys move differently than middle-aged women, who move differently than athletic guys, who move differently than government bureaucrats.

If you look at a lot of animated movies, they don't pay attention to how things move through space.

If you move something 10 pounds through space and then stop suddenly, there's a little overshoot. When you transfer weight from one leg to another, there's a certain way that it happens

Even in hand drawn animation, humans are widely considered to be the most difficult to execute, because everybody has a feeling for how they move.