People's attitudes toward the supernatural (paranormal, ghosts, mysterious happenings, witches, etc.) would have been the same (or perhaps much more intense given their lack of understanding of the natural world as we are blessed with) as they are in today's world. Keep in mind that people in Shakespeare's time were much more superstitious than people today since advances in medicine, science, and technology give us a little more of an advantage over the citizens of the Renaissance period. However, people are always curious about these types of events, and a visit to any large bookstore will prove this. There are huge sections devoted to witchcraft, the supernatural, paranormal, mediums, and fortune-tellers. If there were no interest, these books would not be written, much less sold.
The humours in Shakespeare's time relate to the belief that there were four chief liquids of th human body--blood, phlegm, yellow bile, and black bile. They were considered closely related to the four elements (air, fire, earth, water) and when out of balance, effected a person's health. Blood like air, was considered hot and moist; yellow bile, like fire, was hot and dry; phlegm, like water, was cold and moist; and black bile, like earth, was cold and dry. By 1600 it was common to use the word humour as a means of classifying characters. There are many examples in Shakespeare where we might find the reading to be figurative, but the Elizabethans took as literal..."my liver melts" would be one such example.