Your ragdoll, being attached to another object, is moving in the local space of that parent. Thus you have to make the camera a child of your ragdoll if you want it to follow. Read here for an existing answer: In Unity, how do I make the camera follow a character?
Having said that, don't do it but use a proper script where you set the ragdoll as target to compute the new camera position from. That will give you a much better control and user experience.
For the ragdoll, add a Rigidbody component. The ragdoll is affected by physics and doesn't change its transform's position, adding rigidbody is a workaround cause it changes the transform whenever the ragdoll (parent) changes positions constantly. the ragdoll is affected by rigidbody but it is barely noticeable. Make a script or add a script that constantly changes the camera's position relative to the ragdoll (add some offset if you're doing third person or want the camera to be positioned onto the head). This should make it work.