@anon763
If you are looking for a point, take note that demons represent a complete lack of empathy, a lack of common shared values and humanity. For demons, these concept are completely foreign, and they are merely capable of using the same words, but not understand the meaning behind some of them.
In the beginning of this manga, we were presented with the fact that some humans, namely those who commented on Frieren's behaviour at the hero's funeral, considered that she lacked empathy.
This couldn't be further from the truth, and over the chapters, we have been presented with the myriad of subtle ways in which she displays her empathy and humanity. Of course, she does not attach the same value to certain aspects of her life due to how she experiences them. Her humanity appears to be faint. For instance, you can contrast the demon's complete lack of understanding of what a family is with how Frieren understands it. Frieren understands what a family is and had one, but she hasn't seen them in several hundreds of years and hasn't even met another elf in that period. Her values in that regard may appear monstrous.
I'm not sure why you thought there would be a twist here. It's just interesting to see that humans forget about the nature of demons and repeatedly project their own empathy on them, and yet are just as capable of seeing a lack of empathy in Frieren due to her behaviour as she does not attempt to deceive them in regards to how she values and experiences events. It's like judging a book from its covers, and humans continuously do this, labeling others through a single interaction or a trait when this is never enough to determine someone's "content".