It's because this type of する means "to work as ～", "to play the role of ～".
娘, 子供, 赤ちゃん and so on are not the name of a role/occupation, so you cannot use する with them. 主婦をしている is okay if you think it's your job.
学生をしている is a gray area case and sometimes ...
All Japanese quantifiers are adverbs. 全部 is an adverb too, meaning "wholly" or "entirely". That means, it is true that it can be ambiguous like "Are the windows all shut?" between "all windows" and "completely". That said, the "all of" reading usually prevails, and also the most common way to say &...
I believe 在る here is used not as part of the copula である but in the actual literal meaning of "to exist". This is partly hinted by the use of kanji instead of kana (though it is not a 100% indicator with manga).
I.e. the meaning is roughly:
"people tend to forget that they exist as humans"
"people tend to forget that they're ...
Do these guidelines for choosing の/こと apply to the use of ということ and というの? If so, those guidelines don't seem to be followed in a lot of the example sentences I've read.
In the sense that you should keep collocation with predicates, basically yes. In the sense that you can add という, no.
Am I overcomplicating this? I've read and heard suggestions it's as ...
You can rather straightforwardly translate 違いはXにある to "the difference exists/lies in X". X can be a noun phrase or a noun clause (i.e., "in that ～"). This ところ refers to an abstract "point", but it can be replaced to こと here. I think there is no significant difference in meaning.
The difference lies ...
場面: scene in the sense of "situation"
光景: a memorable scene seen by one's eyes
情景: scene in the sense of "vision", something imagined in one's mind
景色: wide scenery/landscape (typically of nature)
景観: beautiful landscape (e.g., of a city) maintained by people
眺め: scenery/scene seen from a distance (眺める = to see from a distance); ...
My answers to your questions are as follows:
God knows. I can't speak for the author. They may have wanted to avoid repetition out of personal preference, may have been just following the house style (if there was any), or may have just written it that way without thinking about it at all. What I can say, however, is that they definitely could do it and ...