Most stories are unoriginal, if you want to be honest. I mean...there's literally novels about how all stories can be narrowed down to seven things.
[hider=For those not in the know.]
'Man against man'
'Man against nature'
'Man against himself'
'Man against God'
'Man against society'
'Man caught in the middle'
'Man and woman'

Or alternatively,
'Overcoming the monster'
'Rags to riches'
'The Quest'
'Voyage and Return'
'Rebirth'
'Comedies'
'Tragedies'
[/hider]So maybe people at large simply like the familiar. Or at the very least, don't know what they want. (But it's certainly not always originality.) Though unlike many novels, I can't say I've ever seen more unique experiences coming from writing than in Roleplaying itself. Where you have many potential writers, all with different abilities, styles, etc. Some that even game-ify the concept. Separated from tabletop or text-based games. (Albeit, not many on this forum.) But I'd argue I see plenty of originality or lack thereof in both 'original' and 'fandom' ideas. And as it was already covered, using tropes in writing aren't automatically a negative. Since if it's used all the time...it's usually beneficial to/liked by the readers. 

But to keep it brief, since it's already going downhill fast, if you can't find something original. Maybe, make it yourself.