It is the lowered head that makes her seem less mobile than, say, a horse, or a deer surprised in the woods. More exactly, it is her lowered head and neck. As she stands still, the top of her head is level with her back, or even a little lower, and so she seems to be hanging her head in discouragement, embarrassment, or shame. There is at least a suggestion of humility and dullness about her. But all these suggestions are false.