Originality is a big hang-up these days. One of the first things I tried to do when I first decided to become a writer (all the way back when I was about 11 or 12) was come up with totally new and unique ideas that had never been done before. Years have gone by and I've thought back to those ideas I had when I was so young. I learned something, too.
It had all been done before.
The dreaded "unoriginal" label is something all writers hope to avoid. This can lead to a belief that the best way to make it in this industry is to come up with the most amazing plot twists or a concept nobody else has thought of. Unfortunately, this isn't really the case.
There is a limit to the variety of plots and characters that can be used. The fact is that almost anything you can think of has probably been done before, and there's a reason so many tropes keep coming back. It's because they work. People like seeing them.
Certaintly, there's room for an unexpected twist or a really novel take on an old favourite, but by and large readers can lose themselves in a book much more easily if they're not trying to wrap their heads around your latest, greatest invention. When I write, I try to focus on telling a good, fun story first. Rather than coming up with unique ideas, I try to use established tropes well, or even apply them in ways that are just a little different from what may be expected.
So keep writing and keep working. Don't sweat it if you think your work is similar to someone else's. Don't worry if you can't come up with something new to happen to vampires when they're exposed to sunlight, or that you want to feature elves or dwarves in your fantasy novel. Concentrate on telling a good story, and telling it well. The rest will fall into place.