Great illustration of the size concept, but the lighting needs a lot of work. The planet is not lit so poorly that the baby's feet would be almost invisible in shadow, unless it was night. By contrast, there is a glaring white spot on the baby's shoulder that is very distracting, and is matched by the overly bright spot on the diaper.
The elephant "toy" (EXCELLENT size emphasis for the image) should have some sort of harness, instead of the cable just coming out of his back, and shows a rough extraction edge and some white pixels ~ Try using the Extraction Tool or the Pen Tool for better edges.

Consistency and edges are the key to good Photo-chopping, and you cannot "cover up" inconsistencies by simply making everything dark.

Well said MossyB. I think you said enough for everyone. But it is a cute idea