When I was a kid some relative gave me a copy of How Green was My Valley by Richard Llewellyn. I liked it so much I read it in one long sitting. Did I truly comprehend it? Not a chance. I had never heard of Wales and I knew nothing about coal mining. As far as I was concerned the story could have been about plutonium mining on Mars. I read the entire book thinking the main character was named "Huh-wa", and his friend was "Mr. Gruff-id": I finally reached the last page, "How to pronounce Welsh names", and discovered the book was about a boy named Hugh and his friend Mr. Griffith (with a soft "th").
My grandmother had many cartoon books; at her house I was introduced to the great work of Charles Addams. She also had several Andy Capp books, which I read over and over with great interest but little comprehension. What was this world, where people used strange vocabulary like "owt", "nowt", and "summat", where the husband rolled home from the pub at 2 a.m. while the wife waited behind the door wearing a nightie, curlers, and big fluffy slippers, with an upraised rolling pin in her hand? It was a mystery to me but I kept on reading, hoping I could find the clue.
I read and enjoyed all the Little House books as a kid, but it was only when I reread them as an adult that I noticed that Laura Ingalls' family was poor, while Almanzo Wilder's family was rich. As an adult I was much better able to appreciate the story Laura Ingalls tells about her wedding. She told Almanzo she didn't want to promise to obey; he replied, "...it is only something that women say. I never knew one that did it, nor any decent man that wanted her to." [The year was 1885!]
We all bring varying levels of comprehension and appreciation at different points in our lives. And so what? Anything worth reading is worth being confused by.
The current hyperventilating about "comprehension" is one more way that we make reading a dreary chore. Kids don't need to comprehend everything all the time, and they especially don't need to prove their comprehension all the time. Let them be.
Overachiever's footnote: "owt", "nowt", and "summat" are examples of Yorkshire dialect. "Owt" = "anything"; "nowt" = "nothing"; "summat" = "something".