Every culture believes in ghosts and haunted houses. Even some in the NT thought Jesus was a ghost/spirit and also Peter.
Why the universal cultural belief in ghosts and what are they?
Every culture also believes in haunted or enchanted places or houses or relics.
What is true?
This discussion seems to have gone--immediately, really--far afield from this question, although since the original poster participated so heartily in the discussion, perhaps not.
I think that the question, as put, should be answered along these lines: There is a universal belief in the unseen and spiritual because we are created in the image of God. Part of the broader image, as many theologians have argued (along with things like personality, rationality, morality, authority, and creativity), is spirituality. Man is a spiritual being, having eternity in his heart, and he knows that there is something more in the world than what one simply sees. He knows that there is an unseen reality. Though he may be a naturalist, in his heart of hearts, being marked at the core of his being with spirituality (God is a Spirit), he is not truly anti-supernaturalistic, whatever he professes to be.
However, man in his unregenerate state, suppressing the truth as he does, perverts the supernatural. He ends us adoring Satan and his minions, either directly (in rarer cases) or indirectly (in most cases, including the false religions and Christian cults). As a part of his perverted supernatural beliefs, he turn to all sorts of things instead of God.
Some of these things may involve really existing evil spirits and some fictional ones. It doesn't matter whether the particular evil characters are real or not because it is the Creator, who alone is to be worshiped and adored, and not the creation (malevolent spirits real or imagined).
There is a universal belief in the supernatural and it manifests itself either in truth (with one worshipping the true and living God) or in falsehood (one worshipping the creation, under whatever rubrics, rather than the Creator).
Peace,
Alan