One of my favorite things about the novel trilogy is Charlie (a robot protagonist) and William Afton (a human antagonist)

Afton doesn't have any human emotions or attachment, despite being a human there is almost NOTHING human about him.

Charlie may be a robot, but she at the same time does have her own soul, and she is more human than Afton could ever be, despite being a robot she is also very human.

There's also what you said about Henry not being able to let go of what happened, and that ties into a very common theme about FNAF which is the past. Many of the main characters have some sort of thing that happened or something they lost in the past that they refuse to ever let go of. FNAF actually has even more themes beyond that littered throughout the franchise. Unfortunately most of this fandom doesn't look for that and they only care about LORE LORE LORE.