I try to be fair when watching something that clearly knows what it is. Pumpkinhead is an exception to that rule.
At its core, this film takes a plot element from Deliverance (no, not the squeal scene) and goes further. In that film, the folks in the country are portrayed (among other ways) as distrustful of authority outside of their own rule of law. Same goes for the protagonist here (played by Lance Henriksen) and those around him as he seeks vengeance on the evil city slickers who wrong him. He should have just called the cops instead.
(Image courtesy of Horrorstew.com)
A Plot With This Many Holes is Called Swiss Cheese
The film starts with Ed (Henriksen) seeing a man destroyed by a tall, vicious creature outside the family farm house (mostly in shadows). His family doesn't get involved because they think it's not their affair. So much for being neighborly.
Flash ahead to years later where we see Ed running some sort of general store in the same rural, desert area with his young son. There is a perfunctory scene or two to establish the bond we all know is about to be damaged or severed in some way. The boy gives Ed a necklace that only a boy could make. We'll see this later.
A group of young adults — "the city slickers" — comes by the store getting ready to ride their dirt bikes rather recklessly around the area. Next thing you know, Ed's son is badly injured in an accident. A few panic and run, a couple stay behind to wait for Ed to return from running an errand. He does, the teen confesses what happened, and Ed snatches the boy's body up and flees after giving a fierce look at the kid.
Back at their place, the young adults fight over whether or not they should call the police with the one who hit the boy, even locking a couple up in the closet.