Humor, Comedy, and Tragedy in TLR

I've attached a Voyant ngram of "Humor, Comedy, and Tragedy" in The Little Review.  These topics interest me because I typically consider Modernism to be a hyper-serious artistic movement.  The words "comedy" and "tragedy" uphold this concept and "comedy" is used much less frequently, suggesting "tragedy" is more important.  "Humor," however, appears just as frequently as "tragedy" and follows a similar pattern.  

Based on our discussion of TLR 5.5 (and the "Hades" episode of Ulysses), I don't really know how to read the ngram data.  None of these words appear in this issue of The Little Review.  This issue has less critical analysis than other issues and art does not typically categorize itself explicitly.  The similar trends of "humor" and "tragedy," though, suggests an unexpected relationship that I'd like to know more about.  Obviously, whether something is funny or not doesn't rely on using the word "humor," but these trends show that the editors were interested in humor as much as tragedy.