I think we're mixing two ideas again.
There's a difference between being "original" and the first to do something.
So when someone quips that "Everything has been done before" that doesn't apply to being original.
The term original is reserved for the thing that is being copied as in the Originator. Origin. The start...implies there is something after...
There is not an original without a copy.
So this means there are a million ways to be original (or have an original take) with something that has been done before.
As an artist it's your job to know your medium(s).
If your thing is to make comics, you should know more about them (and [have] read more) than the average fan.
And what is original (or rarely done) to YOU should be more so to them.
That's one of the buffers against accidentally copying (having similar) ideas and stories and lore and, and...to other works.
The "Origin" of your story may be familiar or has a common setting or tone or set or plot, but over time, you're supposed to express the YOU and that's where the originality is supposed to kick in.
You make a new and unique dish with common ingredients.
This is also about the artist' journey which (broadly) goes from copying to doing stuff that hasn't been done before or simply isn't being done so you still get the credit of being original (and sometimes even the first).
The two steps to being (more) original are
1) Know the history of you medium/field/passion/hobby
2) Find your unique voice as in - what do you want to ADD as opposed to just wanting to belong, which is where EVERYONE starts.