.
If you went to Amazon, go back there and read the reviews. You will see there is a controversy as to which order they should be read in...the publishing order or the chronological order.
This should indicate to you that the order in which they were first published, the order in which Lewis wrote them, was NOT the order of the set you have. The publishers decided to re-arrange them.
If you haven't read the books recently, go back and read The Magician's Nephew. You will see that when Lewis gets to the creation of Narnia, he is obviously explaining something that he assumes the reader already has read.
Great. You've got the "revised" order, not the order in which they were written.
I'm glad that you found the revised order to be easier to follow. I didn't have any trouble with the original, and as I said - it actually made for some great "a-ha!" moments, when I discovered a little tidbit about a previous book.
I notice that you mention that the publishers rearranged them AFTER Lewis' death. Do you suppose maybe it was because he wrote them in the order that he intended them to be read in? MO - it was unnecessary, and probably done by publishers who didn't want kids to work their poor little brains too hard. I would also note that someone decided to release the first book written as the first movie.
But - the bottom line is that you could read them in any order and they would be good books. And the movie was quite good.
I really hate to get into the whole numbering controversy again but I just have to interject here. The fact that you have a picture of books published in the '80s with numbers on the spine that show "Magician's Nephew" as #1 is not "checkmate". ("Aha, here are the numbers! See! That proves it!")
The ones I read as a child in the '70s were numbered too. In the original order. Here's a picture of them:
The LW&W is book #1. The Magicians Nephew is #6.
However, neither my numbers nor yours prove anything definitive. Publishers can choose to put any number they want on the spine. The numbers on the spine in your '80s books or my '70s books are irrelevant to the question.