why in the movie it why does he kill little kids and does he kill certain people?

It is a 1986 horror novel by American author Stephen King. The story is about seven children being terrorized by a shape-shifting, child-killing malevolent entity - known as "It" - that takes the form of their deepest fears but primarily appears in the form of a clown, calling itself "Pennywise the Dancing Clown." The novel features a nonlinear narrative which alternates between two different time periods and shifts among the different perspectives and stories of its seven protagonists. It deals with themes which would eventually become King staples: the power of memory, childhood trauma and the ugliness lurking behind a small-town facade.

pennywise only kills because they belive, when they get older and they stop beliving they can't see him anymore

bc he was born too hurt ppl and he were burnbut the right too kill children so idk whats wrong him to so forget him@@@@?:::::::::- tri of itt