I think we saw two entirely different movies. The female lead being pregnant and being in a wishy washy mood over it and then dealing with demonic possession and protecting her sister's children definitely fits in with it. I'm just going to assume that you went to take a piss during those scenes or were outback smoking crack. Either extreme.
The whole thing with the dad was setup for why they're in this current situation and it does pay off later with the little girl and the mother outside.
And there was no payoff with them. The entire point of "J" was that he left the family, and Beth was dealing with her own thing too when that he left. That was the
starting point of it.
There could be some family conflict before all hell broke loose. Maybe Ellie could be explored more before she turned, making it ambiguous how much of taunts are from the demon or repressed feelings, like she struggled on being a single mother, which is a thing Deadites commonly use to absolutely toy and destroy a person emotionally because nobody can know if its the demon or the real person.
Maybe the family could have a scene on everyone finally snapping from stress and pointing blame tearing each other about the divorce (bonus with again, the deadite adding to it, forcing the trust further apart). But the subplots are just simply there, simply existing.
Hell, the film could end on J just doing whatever in wherever he is, unaware. It could work as one of the many possibilities of a payoffs, a humourous but absolutely dreadful one in dramatic irony. Maybe with a bonus with the 'reborn' deadites of the family aiming at him instead of the blond girl for a really oddly done bookend.
Going back to 2013, Mia’s addiction tied into the story on why they were at the cabin and put an actual reason of everyone didn’t believe there was something wrong when she turned. Rise has story points then abandoned them to make some for some generic blood-filled movie. It even has a page in the book where a baby was bursting out of a woman chestburster-style, which made me think something got cut like I mentioned before.
This is a longer post than I intended, and I know it’s more important to look at films for what they are as opposed to what I’d like them to be in general. But I think the fact of making of all these what-ifs and poking at characters speaks to how sheer okay-ness Rise is in general for missing opportunities they put in their own script. Its decent, not good, but not bad either- but it could gone so very easily above typical and generic horror fare and into having actual Evil Dead insanity, if its just... uses them and didn't hold back.