I don't know this for sure but if an author has something to declare and they can't back it up it's just an idea. So if you want to identify the claim you have to have statistics and facts to prove what you're saying. But remember I am not am expert so whatever you think the answer is go with it. Hope this helps ;)
The plot structure intrigues readers because it takes place over a long period of time.
I would interpret it as how people only look at reality, not what's inside or what they can't see.
If the sentence in question is a statement (ends with a period), I would probably "however" as your transition word.
