Oh, constantly.
I think this fear is an extremely common one among creators.
Years ago I was walking through a used book sale and thumbing through worn out paperbacks that I'd never heard of. I had this weird thought when I realized that I was potentially holding years of someone's work and it was two steps away from a garbage bin.
Fast forward a year or two, and I kept having breakdowns while working on a novel that I "didn't want to be like anything else anyone had ever read". The process was grueling. I was taking myself way too seriously. Every step was like I was mentally grappling with imaginary critics and trying to claw my way into the public imagination. For some reason that used paperback bin full of old romance and pulp fantasy novels continuously terrified me. I kept working on this thing, regularly staying up until 3 AM slamming out words and later deleting them for maybe three years.
...And last year I got burned out. I stopped writing entirely and sort of screwed around. Made some dumb comics, read some bad fanfic, watched a lot of garbage TV in the time I previously would have been forcing words into a google doc.
Some months later, I got an email from someone who had followed a (really terrible) comic I made back in 2012. Long story short they wanted to let me know that they thought about it occasionally and hoped I was doing okay.
So I realized a couple things here.
-Someone out there loved a shitty, unoriginal comic that I made nearly eight years ago and still thought about it.
-I can list dozens more shitty things that no one else really knows about that I love and regularly think about including fanfic and extremely tropey and unoriginal books, movies, and television.
-The only person who knew of the book I'd been writing for years was me, and even I can't really think fondly of it.
So here's the takeaway from all of that which has helped me stay motivated.
Maybe you won't be a media giant, and maybe the thing that you make won't revolutionize genre. (Or maybe it will! Who knows.) But regardless of the outcome, if you share what you make, someone, somewhere will resonate with it and it will be remembered.
Have fun with your work and create it with love and passion.
Imposter syndrome will hit sometimes, and it'll hit hard. but so long as you love it and keep going, I PROMISE your work won't be forgotten, regardless of similarities it might share with anything else.
tl;dr: believe in yourself, it'll be okay.