This photo was published in December 1903, in the Current Books section of The Book-Lover magazine. It's a bit of a mystery, as it's not a standard kind of Denslow image. I think it may be a picture of a store display designed for the sales of Denslow's picture book series. It's a charming piece, and a three dimensional sales tool like this would have been very eye-catching!
The idea isn't too farfetched, and it seems as though it could be related to this other display, for Denslow's Mother Goose. The Mother Goose piece had a clockwork mechanism to make the goose raise and lower her head while her beak opened and closed. I've seen the Mother Goose display in person, some years ago, but who knows if Humpty could still survive!