Well, this is a very interesting topic to me. I have said here before that I often think in images or pictures, and
very much wish that I could transfer these images to the intended recipient. For example, I'd like to send either one of my kids an image of their room perfectly cleaned, and know that they cannot mistake my meaning (oh, I didn't know you meant under the bed, too!).

I haven't read or done any studies, but I should think that most people think in images, don't they? What comes to mind when I ask you about your first bicycle? A favorite
birthday celebration? Wouldn't it be wonderful if we could
get across to others, not merely the description of how we felt, but the actual feelings themselves? Oh, the thrill/fear of my first "big" bike, and the terror when the chain fell off! And sounds, too--they could "hear", not my actual childish scream, but my memory of it.

I can't guess how a person without language would think, but surely it would have to be in terms of something he'd
experienced. To take your example of a wolf-boy, perhaps if he is very hot, he'd think of himself in the river, and how cool, wet, and smooth the water feels to his skin?

I think Brandon, whom I was delighted to find a post from today (yesterday?), would be the best-qualified person here that I know of to say how deaf people think of language.
I somehow doubt that thinking in sign language is common.