I've long maintained that orginality is at least somewhat overrated. In a world with billions of people, it's very unlikely that you are privy to wholly original idea that no one has ever thought of.
Author Natalie Whipple puts it better than I could:
We writers can be really weird about our ideas. Sometimes we love them like people. Sometimes we doubt them or feel as if they betrayed us...or we betrayed them. We can be wildly possessive over them, and we really want to think that we're the only person EVER to have a certain idea for a story.
The truth is—other people are going to have your ideas.
Also, that is OKAY.And, not only that, it can even be helpful. Authors can sometimes serendipitously tap into a trend started by another author just because they happened to simultaneously be writing something somewhat similar.