Hello friend
Your experience is interesting because it reflects a change in belief in the supernatural. Initially, you stuck to the principle of following evidence and facts, not believing in things like ghosts and paranormal things. You also think of horror films as something funny rather than scary.
However, an incident at your grandmother's house changes your perspective. The sound of footsteps in the corridor at twelve o'clock at night that sounded like someone running in a robe evoked real fear. This shows how personal experience can undermine a strong belief in something you previously thought was not real.
greetings, good luck