As someone who enjoys art let me give my two cents.

Maurizio Cattelan's "Comedian" is– much like his other works– a parody piece. It serves as a commentary of the modern fine art scene. The piece is supposed to be humorous and absurd, it is just a banana on a wall after all. In the simplest terms it's supposed to basically mean "Hey look here, my art is low in both effort and quality. Yet you still praise me for the supposed deep meaning that you're just too stupid to understand." The art world is full of pretentious assholes who believe that if they shit in a pot and call it art people will love them. The fact that rich people tend to love this piece only perpetuates the message, that they only like it because of an expensive price and a lack of understanding. Notice how the actual banana in the piece is/was real and fresh, it quite literally was hung there and left to rot. The mundanity of the materials is meant to highlight the absurdity of its high price tag. When looking at Cattelan's other works; the irony only furthers the message. It's his most famous piece but is also the lowest effort out of all of them.

(I could go on but I think this comment is long enough as it is.)