Personally, due to lack of details of Simon's character, I don't have a strong opinion on if Simon would make a decent leader.
What does his death say about the boys?
- It shows that the boys were savage and were willing to listen to whatever Jack said. It also shows they were willing to listen to their intuition to kill more than their logic to examine the situation
What does his death say about human nature?
- It shows humans are naturally savage and murderous. They’re selfish and society sucks as a whole
What does his death say about political systems?
- It shows they are needed, otherwise, humans will kill everyone. If we don’t have a proper government, it is total chaos and everyone does everything based of their selfish intuitions