I don't believe writers when they say they aren't derivative: every writer had basic influences early on that left impressions on their writing style. I read a real lot when I was younger, and I tended to read European authors like Jane Austen and anything by the Brontes. I also read Frankenstein over and over. I didn't understand everything that I read, but since I wasn't required to read those books, they left a more lasting impression on me than say, Johnny Tremain which was required and achingly dull.
Literature seemed pretty tidy in those books. Emotions were veiled and even Frankenstein didn't scare me. Somewhere in my 'tween mind, I got he was a symbol.
Then I read Catcher in the Rye. It was as if I had been slouching around reading and this book made me sit up. He talked about places I recognized, like the duck pond in Central Park. He talked about having panic attacks. He talked about telling lies. He openly talked about not being happy.
I remember telling my English teacher I was reading Salinger. She snorted, "That book is like one long complaint."
Still, I read it over and over. I think I was about 12 or 13 when I read it. I read it again at about 16 and understood a lot more. I even looked up what a field of rye might look like back when you had to use an Encyclopedia Britannica. It pretty much looks like this:
All kinds of things are being said about Salinger now. I don't think he began YA as a genre as a lot of bloggers and interviewees are saying. I'm not sure if he spoke for a generation as that generation is now approaching 100. Maybe he did at the time.
What he did do was write a really, really good book that spoke to teenagers in a way that made them feel connected to someone else through literature.
Pretty much, that's the whole point.