In the Armature modifier, remove the selected vertex group (Body). But anyway there are some vertex groups missing in the mesh, for example the fingers, so the armature won't be able to control it correctly. So maybe remove the Armature modifier, join the head object to the rest of the body, shift select the armature, parent With Empty Groups, then switch the character to Edit mode, select each part and assign it to the good vertex group. It should work fine.

In the Armature modifier, remove the selected vertex group (Body). But anyway there are some vertex groups missing in the mesh, for example the fingers, so the armature won't be able to control it correctly. So maybe remove the Armature modifier, join the head object to the rest of the body, shift select the armature, parent With Empty Groups, then switch the character to Edit mode, select each part and assign it to the good vertex group (select the vertices with L then go into the Object Data panel > Vertex Groups, select the group in the list and click on Assign). It should work fine.

In the Armature modifier, remove the selected vertex group (Body). But anyway there are some vertex groups missing in the mesh, for example the fingers, so the armature won't be to control it correctly. So maybe remove the Armature modifier, join the head object to the rest of the body, shift select the armature, parent With Empty Groups, then switch the character to Edit mode, select each part and assign it to the good vertex group. It should work fine.

In the Armature modifier, remove the selected vertex group (Body). But anyway there are some vertex groups missing in the mesh, for example the fingers, so the armature won't be able to control it correctly. So maybe remove the Armature modifier, join the head object to the rest of the body, shift select the armature, parent With Empty Groups, then switch the character to Edit mode, select each part and assign it to the good vertex group. It should work fine.