As mentioned in another comment here, I Googled the definition of "earnest", and it mentions "sincere and intense conviction". My post focuses on sincerity whic

As mentioned in another comment here, I Googled the definition of "earnest", and it mentions "sincere and intense conviction". My post focuses on sincerity which (perhaps in an extreme form) seems to require honesty and an aversion to misrepresentation. This kind of aversion would seem to make play and humor harder. Still, the above chain of reasoning is longer and less convincing than I thought it would be.