Chekhov's Gun or "Why I'm Not Writing Elves" (Worldbuilding Part 2)

"If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there." 
   - Anton Chekhov

Sometimes called the Law of Conservation of Detail, the rule of Chekhov's Gun in writing makes a lot of sense.  If you're going to write about something, write about something that actually matters to the story.  Otherwise, why include that detail at all?

I could write a whole lot more about Chekov's Gun, but what I really want to write about is how it applies to world building--specifically in the use of sentient non-humans.  Don't get me wrong, I love stories with elves, aliens, dwarves, robots, etc. (just look at my bookshelves).  I'm just not inspired to write a story that has the human/other race conflict as one of the central themes of the story.  

"But you could write a story with non-human characters and make some other conflict the central theme!"

Actually, I couldn't.  Because of Chekhov's Gun.  Remember, the principle of Chekhov's Gun is if you include something in your story, it should be important.  And a whole other species of sentient beings is a lot bigger than a rifle hanging on the wall.  Humans are easy.  We're all human, and human interaction is our default setting.  But non-humans are different, for precisely that reason.  They aren't human.  If you're just writing humans with pointy ears and calling them elves (or Vulcans), why do you need the pointy ears?  There has to be something different enough about them to justify creating a whole other species--otherwise you might as well just write other humans.  Once you've figured that out, you have to show how they are different than humans, and how they're the same.  And if you've invested that much time and effort into explaining how your species is different from humans, those differences should be important to your story.

"But there are lots of stories with non-humans where the human/non-human interface isn't critical to the story!"

Possibly, but I can't think of very many, whereas I can think of any number of prominent sources that do:

Lord of the Rings:  the differences between Men and Elves (namely immortality) is the entire motivating force behind the creation of the nine rings of Men.  It's why the Elves managed to keep their rings of power.  Oh, and it's the central premise behind the Aragorn/Arwen love story.

Dragonlance:  Tanis Half-elven, the primary hero of the original trilogy, has--as his primary internal conflict--an inability to balance the human and elven sides of his lineage.

Discworld:  this is an exception to the rule, sort of.  While all of the Discworld novels have multiple species, not all of them feature inter-species relationships as a central theme--but a lot of them do.

X-Men:  human/mutant relations is the central theme of well, everyone.

I could go on, but you get the idea.