system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is Humpty Dumpty often times depicted as an egg when the nursery rhyme does not mention him being an egg?
gpt
One likely explanation is that Humpty Dumpty used to be a riddle when it was created. The answer to that riddle was "an egg". 
However, over time it would gain popularity and become a well known nursery rhyme, taking the form of a story instead of a riddle. This allowed for Humpty Dumpty to become a character portrayed as an egg.