It's fairly direct and straightforward. The entire film is basically a tense portrayal of an alien on a task of harvesting humans being shoved in human civilization. Sort of like an alien coming of age story, her/it slowly learning empathy and compassion and then being confronted with the polar opposite at the end.
The fact that they shoved shoved ScarJo in the middle of Glasgow is perfect for the narrative, she might aswell be an alien when compared to the average Scottish dude
>her/it slowly learning empathy and compassion I get the first part, but it seemed to me that she already knew how to behave in a manipulative way to allure the men
First she only manipulates in order to harvest the humans, but after she meets the disfigured dude and experiences empathy and compassion through humans helping her when she falls etc she stops harvesting and then literally tries to live as a human ultimately fails to do so