They say all the good stories have already been told. (I'm not sure who "they" are, precisely, though I envision hoary old men, much like my 10th grade English teacher. Who I revered, by the way, much like my 11th grade teacher only with a certain amount of fear. Mind you, that's a different "they" than I envision for grammar... which is embodied by my 9th grade teacher and a coworker I once knew. They could have been sisters, only my coworker was also far less scary. Come to think of it, it seems like every other English teacher I ever had exuded that scary vibe. Hmmm... oh well, that's another post entirely.)
As any writer/reader knows, to some extent "they" are right. All stories boil down to a few simple plot lines. (Add a little salt and some celery and you have soup.) Usually these are defined as the "man vs" stories, though that's probably passe and not in keeping with gender-neutral stories. Though "person vs" doesn't quite fit. Not to mention it's not always people anyway. "Watership Down" was about rabbits, though as with any animal as protagonist book they were at once stand-ins for people and a way to look at ourselves without appearing to scrutinize ourselves too much.
Or simply a way to approach otherwise unapproachable subjects. I was in high school before I read "Dracula" but back in middle school there was "Bunnicula." The average 6th grader isn't tackling wooden stakes and sexual undertones, but vampire rabbits - and well-meaning but slightly insane cats trying to pound a t-bone through the bunny's heart - those are doable. And still funny three decades later.
Which brings me around to my point, despite the meanderings. All the stories have been told, of course, but it's the way in which they are told that matters. "Romeo and Juliet" is essentially "boy meets girl," and "West Side Story" is essentially "Romeo and Juliet" set to music. Catchy music, no less. Sometimes even telling the same story can be important if you change who is telling it. I was listening to a story on NPR the other day, and a reviewer was commenting how he has seen a specific opera probably a dozen or so times. And yet the last time he went to see it, something about the performers at that time made it more poignant, more involving.
"A Christmas Carol" has been told hundreds of times, but I still prefer to hear Captain Picard do it. (My apologies to Patrick Stewart for typecasting him. He was also excellent as Professor X. ... No, seriously, he's a good actor.)
So just because it's been done before, doesn't mean it can't be done again. Or done better.