Who are the horror characters?

I thought it was really interesting how these supernatural elements exist from other past supernatural film. When I was watching the film, I realized that these characters are the sames ones I've seen in the past. For instance, the clown, is seen in many scary movies. What I really didn't understand was why the directors required people to get murdered in some horrendous plot. Why didn't they just kidnap people and instantly murder them without the risk of an apocalypse. 

This film also reminds me of a metafiction because the film takes place in two worlds. One manipulates life to save all of humanity and to keep an evil monster contained, while the other world consist of college students having a summer cabin trip.