Hi, Kristan. It might help to remember this when you're being insulted as well as when you're being flattered: "Consider the source." Was it anonymous? If you know who it was, did it come from someone you respect? If not, how much are you going to let it matter to you?
A comment at the level of "your stuff is bullshit my poop has more creativity" speaks volumes about the person behind it. I could really go to town and pick it apart, and in the process I hope you can see how to view things like this in the future.
First, the person uses lowbrow language and cannot manage to string together one sentence with any punctuation and capitalization (granted, this only matters to some people—myself included, as I am a writer/editor by profession). Second, the lack of manners evident in this person automatically lowers my esteem for them, and when I don't respect a person I don't give a damn what they think—of me or of anything else. Third, there is no foundation for the argument. HOW is his/her poop more creative? Any proof offered? Pictures? Concrete examples? Logical reasoning? Fourth, if the person uses poop as a gauge of creativity, is he or she mentally stable? Do you want to engage in a battle of wits with a person who is unarmed?
A bully uses putdowns to feel better about himself/herself.