What I'm being at is that all of the things you said are there, absolutely, but they're all in service of the bigger theme of what it means to Parent. Dahlia is Alessa's mother, sure, but she forces her into a role she doesn't want and abuses her to make her fit that mold better, ending with her
What I'm getting at*
essential objectification in the form of her being reduced to a living womb for the cult's God. Meanwhile, Harry is just someone who wants his kid to be happy, and is genuinely looking out for her best interest. He has no ulterior motives, no big plan for her, he just wants the kid to be Okay™>
And then, when he can't get that, he loves the kid he gets instead as much as he can anyway. Like, child abuse, grooming, religious trains, etc., absolutely happen, but it's not ABOUT them, it doesn't have as much to say about them. It DOES have a lot to say about what it means to be a parent.
*religious trauma lol