I read this book 50 years ago when I was 16, and the main character Holden Caulfield was 17. Holden expressed perfectly the alienation of a teenage boy who doesn’t fit in because he thinks about the things that people say and do, and realizes that they are all doing what’s expected of them instead of asking whether any of it makes sense.
Holden is looking for meaning and authenticity, and only finds brief snippets of it.