>>24842144 (OP)
When drilled down to generic details and plot outlines and types of conflicts and all that, yes, every story *type* that you can think of has already been written.
What matters, then, are the finer details - that's where the devil lives, after all.
I'm watching a video on the first two Resident Evil movies and the people ripping on them bring up how in the second movie, Jill Valentine is the hyper-competent main character until Alice shows up at the end of the church setpiece, at which point Jill becomes hyper-incompetent because Alice is the director's OC waifu (and his actual off-screen wife). They even go so far as to say "they should've gotten rid of Jill and just kept Alice as the main character". That isn't to say the movie would've been *better* if Jill was absent and Alice was the main character the whole time, but it would've been a *different* movie. Therein lies the rub: What matters isn't the idea, but the execution.
As another movie example, take the two-fer of asteroid disaster films in 1998, Deep Impact and Armageddon. Both of them had a similar premise - an extinction-level asteroid is hurtling towards Earth with little time to stop it - owing to a Disney exec taking notes during a meeting about Deep Impact and kickstarting production on Armageddon as a counter. But the details show where the films differ despite the similar premises: Whereas Armageddon is a dramatic action film (thanks to Michael Bay) that ends with the asteroid completely destroyed and Earth spared of almost all the negative effects, Deep Impact is more a straightforward drama where the asteroid is broken up but still manages to cause significant damage to several places around the world. The same premise resulted in two entirely different films, and it all stems from the execution of that general premise.
Worry that you're copying someone else's work, yes, but don't worry about being "original". Everything is a remix, dude. Execute the premise with your own details.