why making some limbs to come to the keyframe earlier while the other limbs come later make the animation so organic?what's the name of such phenomena?Is this the secret animating skills you don't learn in tutorials?
It is a basic animation technique. I want to say what you are describing is called followthrough but I can't be sure. I've found that this is a really good source of information and tips for a beginner animator. It covers things like this:https://www.youtube.com/channel/UCR4oFFjKQKHj_fCOkBLH61w/videos