Have you considered reading not just historical non-fiction, but prehistorical non-fiction? Once you learn what strange things existed on this Earth in periods of deep time, the beasts and worlds of fantasy seem much less like fantasy.

There’s a YouTube channel by PBS called “PBS Eons” that has some great video essays. And one of my favorite reads through Earth’s history was “Life” by Richard Fortey. Fascinating stuff.

Have you read Gene Wolfe’s Book of the New Sun? I’m not an avid reader, and have only read LotR, and the Dune series in the last two years. I say this because Book of the New Sun has captured my attention more than almost any other book. In the same way that LotR has that “mythological” feel to it, Wolfe has written something that feels like a waking dream. Reading it is like coming across a vision of the far, far future that you’re not supposed to see.

I haven’t finished it yet, but it might eclipse LotR as my favorite book.