I think you guys are missing out on the fact that The New Cop is Namon. So what happened was that Kelly, Amy, and Namon took the potion the right way. The entire setup of the movie is those three playing Granny and the others. They are all left with everything. They are now Rich, eternal, and evil. That’s why Kelly said the “you’ve got potential line”. Dont believe me? Kelly left the potion in the sun. She killed Granny. She wasn’t being inquisitive. She meant to have Granny come back and kill everyone. That’s why she says “they were weak and we are strong.” She along with Amy and Namon planned everything. And yes, the new cop she stares at is Namon. Watch it all back over with a fresh pair of eyes. It all makes sense.
I thought that Margo's arc had the most potential. I was more interested in the Margo character. I wish they would have done a sequel where Margo is the main character and her backstory is revealed.