Horia Gazdovici, 10F
The question of "What scares us?" is a recurring one in the minds of all writers and storytellers in general, and has been so for ages. One of the better answers to the question comes from H.P. Lovecraft, who said that "The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown." This is a quote that comes as only natural from the father of cosmic horror, a type of fiction that dabbles in the unknown and the incomprehensible of the universe.
What is certain, however, is that nowadays it takes much more nuance to scare educated 21st century people than it used to, as our forefathers, humans of a much more superstitious nature, were prone to tremble with fear when seeing a large monster. This does not apply to our days, as the only people who get scared by large monsters with a tendency to have impractically large teeth are children.
Visual imagery can still scare in the right hands, but subtlety is a much more efficient way of scaring. In the 2017 adaptation of the novel "IT", it's not so much that you see Pennywise in the gutters, it's that you don't, yet are fully aware of his presence. Here is where Horror's younger brother comes in, Suspense, which can be used in thrillers by itself, but makes for great horror when generally scary elements are involved. Suspense is a vital element in horror, as it makes the scene or the passage in the book come alive, and makes the difference between a good jump scare and a bad one. Without any buildup, a jumpscare is a cheap way of shocking the audience for a couple of seconds.
As previously mentioned, more primitive people are much more scared by primitive threats, just as we are much more scared by modern threats, due to the fact that these threats do not feel like a fairytale from a faraway land, but a horrible outcome of our reality. This is why films like Rose Red, which show no apparent monsters, or The Shining, are scary because they are odd to the point of terrifying.