Grrr I get really annoyed at any suggestion that every story should be transparent in its root and that a story is 'bad' if it has layers that a younger child can't decode.
I was read the Narnia series by my Granny before I could read and I LOVED it on many childhood levels. I read the series at around 8/9 and enjoyed the new imagery of my imagination and the story, there were words in there I didn't understand, and I completely missed any borrowing of biblical influence (heavy heavy influence) but it didn't either convert me to Christianity nor make the story less enjoyable.
I've read the series many times over many years, each time I discover something new, for better or worse. Whether it be religious mirroring, or the general view of women, etc etc., the series is still a GOOD STORY.
If we all wait until we can understand the layers, decode propaganda, have an educated well informed viewpoint, well we kind of miss the point of growing up. Part of being a child is in the acceptance of a good story as a good story, of suspending disbelief and reality, of going with it, living it in the imagination... I think to suggest that children may be in someway harmed by a story that's woven on many levels, then we're not giving them credit where its due, the credit that a child should have, that it doesn't MATTER.
A child will love a story so much they may return to it as an adult with eyes wide open and either part ways with it, or love it more.