Not sure if ragdolls is the way to go here if you want animations. But if you really want to use them, I would fix my legs on the floor and have some springs of rotation in the joints, so when the forces are not applied, the body is upright. Then, if he gets hit, he will bend a little, but after that he should return to the waiting state (you may have to help him on his way back, for example, apply some forces / torques until he returns to where you want him).
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