Nowhere in the rhyme do they say that Humpty Dumpty was an egg, but a broken man wouldn't make a very cute cookie.
Themed birthdays are something I never had the pleasure of as a child. I mean sure, I had matching paper plate, napkins and cardboard party hats all with Barbie on them, but disposable paper products do not a theme make. I was never a big Spider Man fan as a kid, but now that I'm thirty-something I wouldn't turn up my nose at these cookies.
I've always had a fondness for cameos and even wore one for an embarrassing period during the early 90's when we were all into velvet chokers and snap-crotch bodysuits. I'm really glad my mom never relented and let me get that Starter jacket I begged for. I'd feel much less shame eating a pretty cameo made of icing.