Late reply here but this is worth noting.
CS Lewis, as most know or should know, wrote Narnia as allegory to help explain Christianity.
However, when you say it was written for children, remember, the average 12 year old in the US is more literate than like 90% of adults when CS Lewis wrote Narnia. There were tremendous gains in education from WW2 era and forward due to the rise of the middle class. The same is largely true in most first world nations. People in our modern world seem to either have forgotten or never knew that we are essentially living in the Golden Age of humanity. Even 50 years ago things sucked compared to now.
CS Lewis wrote Narnia with the targeted literary levels of the majority of the people. We just call that “child like” now.