Am I stupid ?

Hi,

I recently challenged myself in reading English books in order to improve my matering of this language (I'm French).

I started strong with Macbeth. It was quit hard to read, but it had version of the book with a lot of explanations so I managed to go through it and it strengthened my confidence.

While thinking I had a good understanding of the English language, I then started to read Lord of the fly... I now feel completely lost.

The dialogues are OK, but the part of the narrator are really really difficult to understand. I am now halfway through the book and I am not even sure if I could summarise what happened so far.

Hence my questions : Is this book hard to read for native speakers ? Is a type of English that could be spoken by people casually ? What book would you recommend to challenge myself while not making me insecure ?