One of the first things I was taught in my college creative writing course was that there's essentially only six plotlines in the world, and every story — be it in a novel, film or TV show — is essentially just a different version of those six.
All those so-called original scripts you have stored away on your computer that you're itching to send to an agent? Yep, they're just using the same plots used many times before. Trust me, I know — do you know how many scripts I wrote when I was younger that are basically just glorified fanfic writings of the plots from "Mannequin" and "Home Alone"? (Note to self: Write a script about a department store mannequin that comes to life and boobytraps against robbers trying to break in.)