levi, I understand where you are coming from. I too was a bookworm in the days when Jewish literature was quite limited, and having grown up on the classics, I find the current frum fare far below par, with some notable exceptions.
Yet, my kids who are also book worms, do have lots of frum literature and don’t make the same comparisons that I do.
In their pre-reading days, I have read to them some of the English language kids classics (including Little House, the references to holidays were surprisingly devoid of religious content, and since I was the one doing the reading, I was able to put it all in context-I didn’t think there was anything wrong with them knowing that goyim have their own holidays, we actually discussed how strange it was that they had so little religion in their lives. It also spawned discussion of how such a lonely pioneer life would be incompatible with a frum Jewish one.) Now they read on their own, so it is no longer relevant.
But you are talking about a teenager, you would find it hard to be able to control what he reads.
As far as Tolkien, although I loved it way back when, I personally would not recommend it or want my kids to read it. First, it is not merely entertainment for some much needed down-time- the series has spawned a cult-like following because of its power- it brings you in to a fantasy world that becomes so real, it has such a grasp on you. They are the type of books that you can’t stop thinking about long after you read it. That could interfere with concentrating on important things, like learning. Also, if you ever read the prequel- I forget what it is called, but it describes the history of Middle Earth’s creation, is very anti-Torah and putting the Lord of the Rings/the Hobbit in that context, makes it questionable IMHO. Which is also why I would not give the Narnia series to my kids, even though when I was young and read them, I had no idea of the theology behind them.