But first, the three trick questions:
Did Shakespeare cheat when he wrote real person fic about Richard III and Henry V? How about Bram Stoker, Anne Rice, Stephenie Meyer, or the hundreds of others who've made bank writing books about vampires?
Did the Disney animators cheat when they paid people to model for their animations?
Did all the winners of the Great British Bake-Off cheat when they adapted recipes they learned from cookbooks?
These are all trick questions because there's only one answer to all of them and that's a shouty, arm-waving, emphatic "No! Absolutely no! Triple espresso hold the milk no."
Little They May Be, But Vital: How Writing Small Has Big Story Impact
Writing Your First Novel: 5 Things You Need to Know
Darcy Lindbergh on writing The Watches of the Night
Creativity does not happen in a vacuum. Given the sixty thousand years of human history none of us has an idea no one has had before. We build our societies, our myths, and our creations on what went before and if that's cheating then every last one of us are bamboozlers.
We are, however, creators adding to the collection of human myths and legends using the voice only we have. Hundreds of people have written novels about WWII, Greek gods, bed and breakfasts, or horses. And every last one of them did something all the rest of them never did: Told it their own way.
That is never cheating.
In the blog entry I linked to above, someone asked Gaiman if it was cheating to write an autistic, hard-of-hearing character, since they themselves are hard-of-hearing and autistic. Gaiman's response was wise and I want to add to it:
Writing is hard enough – finding the time, the focus, the right words – that writing about something you know intimately is a gift, it’s the wonderful bones on which to hang all your other story elements.
If you’re Deaf, write about Deaf characters because who else can do that as well as you? Please write what you know and write what you don’t, just…write. Find what helps you write and write.
That's not cheating.