I read Lord of the Rings when I was 10 or so, and largely remember a story about men, orcs, elves, and hobbits. Since then I've seen the movies many times, but, of course, those abbreviate and take liberties. But I remember nothing about "Valar", "Maiar", and all of these other parties. I only know about these elements of the story because I've read questions on this site - to me, Gandalf was just a wizard, but apparently he's some kind of god? It's actually quite overwhelming!
So I'm wondering - was I a poor reader? Do I have a bad memory? Or is all of this just not in the original text (not including letters, other books, etc.)? Is it something that you are supposed to pick up on through subtle references (that might pass by a 10 year old who probably just wanted to get to the orcs)?