The point of view in the comic is a mindset of sadness and frustration that he (the character in the comic) isn’t happy where they are and neither is the leaf in the mind of the character because it falls off the tree, but for the point of view of the audience, the comic is funny because we, the readers, know that the leaf falls off the tree not because it wasn’t happy where is was previously located, but because it was dead, and oddly enough humans brains tend to think that other people getting hurt is funny. (Is this answer ok...?)