You need to develop similar characters (clones of a starting one) behaving in the same way (idle, running, falling, etc.), but do not want to animate each one independently. Is there a way to animate the first one and save the behavior, so as to animate the other characters exactly in the same way?
You need dedicated software, for example, Cartoon Animator https://www.reallusion.com/cartoon-animator/ or a 3D program
Basically, you can animate the rig of the character and apply that to another one.
Each element of the animation, arms, legs, foot, hand, eyes, etc, are separated from each other and glued together by this rig.
Sometimes due to different proportions, you still need to adapt a bit the resulting animation.
You can bone rig 2D sprites directly in Unity with the 2D animation package, or you can use Anima for the same purposes - though I don't know for sure yet if you can retarget entire animations to new meshes, I know you can save and load poses.
In Modo, my 3D DCC tool of choice, I can animate using IK & FK, save and/or export / import actors, poses, actions, and full animation sequences - both with the character mesh and without - I know Blender can do this too, and has some robust 2D tools these days.
Hope this helps.