Lets say it's a common peasant around 1500 in england. If most people didnt, was there a time they did? Were some areas more likely to have believers? How much more likely was a noble to think theyre just stories? Vampires, werewolves?
It is useful to think of these various supernatural beings - or in the case of the walking dead and werewolves, humans under a supernatural curse - and belonging to one of two types: people believes that werewolves, the walking dead (not vampires, however, in England) and various supernatural beings including fairies/elves could be encountered by the average person in their own midst. Dragons and giants, in contrast, were thought of as existing in a remote past or in a remote place: one was not likely to encounter them in one's own village.
In addition, various studies have suggested that people may have always credited a previous generation with believing "more than today." This is an idea developed by several articles in Peter Narváez, ed., The Good People: New Fairylore Essays (1997). Every period and every place had its share of skepticism, but it is clear that pre-industrial Britain had fairly widespread belief in a wide variety of supernatural beings. Education could increase skepticism, but one would not see a clear distinction between the education and class when it comes to belief until fairly late in the industrial/urbanization game. Indeed, urbanity may have been a more important factor than industrialization.
Darren Oldridge argues that belief in werewolves, witches, the walking dead and the necessity of trying animals at court were all logically consistent in the medieval worldview. It is only when we apply our own understanding of how the world works to historical actors that belief in the undead or supernatural monsters seems absurd. Medievals weren't acting irrationally or superstitiously when they believed in stuff like witchcraft or lycanthropy, but were acting rationally within the intellectual and cultural framework that they lived in and inherited.
they apparently believed in dragons: http://www.reddit.com/r/AskHistorians/comments/tp6hu/did_medieval_europeans_really_believe_dragons/
Off topic, kind of, but if you're interested in why this might be a difficult question to answer you might be interested in 'Did the Ancient Greeks Believe in their Myths?' by Paul Veyne. Obviously it uses an earlier focal point (and might be quite heavy if you're not used to reading philosophy of that sort) but it's broadly about the idea of truth, methods of inquiry etc. in different settings.