The idea of ghosts never made sense to me. Like ooooo I'm flickering this light and making creaky sounds in your house. ooooooo, be afraid! Then what? Just repeat that same thing day after day? Boring!
I think modern interpretation of spirits is very movie and novel based. Every culture has a interpretation of ghosts and even person to person has interpretation of ghosts. I frankly have no belief in ghosts and any ghost can be explained away by squirrels or mice running around. My best freinds mom insists there's a spirit in her home and even conversates with it.
I think depending on the story or culture, the flickering lights and stuff was generally either an attempt at communication with the living to help the ghost - or to instill fear so people would make irrational choices and accidentally die