I know this is pretty stupid but I'm just curious what's real and what's not. Like pirates and Vikings for example I know they are real for example Somali pirates. But I hear witches did exist at one point in Salem,MA. But like Greek mythology,zombies,king kong-could ve related to yeti,skull island-whats actually on that island if it does exist? Medieval Times,Lord of the rings type of stuff like hobbits,orcs,dwarfs and elves,and Dragon's like Smaug from the hobbit. Seriously I'm not being stupid but I have heard medieval times are real like the king Arthur stuff and Camelot. Ghosts,Leprahcauns,Bigfoot/Yeti,Loch ness monster,vampires,werewolves,Frankenstein,robots that could take over the world one day like the terminator or transformers something from outer space might come to earth like that? obviously I do think those things are definitely fake but vampires idk I heard their are cannibals in real life but idk about vampires as well, chupcabra-ever heard of that? Transylvania however is a real place that does exist somewhere in Europe. I already know extra terrestrials are real everyone should know that. Neanderthals/cavemen were real they might of existed in 10,000 BC age with the wolly mammoths,and saber toothed tigers. So all of the stuff I just mentioned tell me what you guys definitely don't believe in and what you do believe in. people with superhuman powers I hear actually do exist but not like mutants or anything but if you know what I mean. Giant snakes,giant crocodiles.sharks or whales that get bigger than their normal size?
First of all, we know very little. Paradoxically the more we know the more we realize we don't know. Every new scientific discovery produces far more questions than it answers. Einstein observed that as our sphere of knowledge grows so does the circumference of ignorance. To me it comes down to what is reasonable to believe and what is unreasonable? Vikings and Pirates are reasonable things to believe in; they do not violate any law of physics or logic in order to exist. Ghosts and poltergeists are not reasonable to believe in because their existence is not reasonable. If it turns out that Vikings and Pirates were just stories and that there is some yet undiscovered force that allows for ghosts and poltergeists than I may be mistaken but based on what we know today I'll go with Vikings and Pirates and discount ghosts and poltergeists. There are things that fall between these extremes. Extraterrestrial visitors may exist. We do not have the technology to visit other star systems but such technology is foreseeable. We also do not know how common life is in our galaxy. If and advanced civilization of intelligent life exists on a nearby star system they may have decided to commit vast resources to visit other living planets but if life is very rare than the odds of visitors being close enough to visit us would also be very unlikely. So this would be possible but rather unlikely. Bigfoots may exist; it seems like we would have compelling evidence if they did like a captured live specimen or at least some remains of a dead bigfoot but there is a slight possibility that a large undiscovered primate may lurk in our woods. There are also things that have an element of truth to them but are mostly false. There are no vampires but there was a rather nasty man called Vlad Dracul or Vlad the Impaler who tortured thousands of people by impaling them on spikes. The Dracula story is fiction but it was based on a real person. Ockham and Hume gave us some very good ways to determine what things we should tentatively accept as real. Ockham's Razor said that the simplest explanation that explains all observed data is the best one. Is it more likely that ghosts exist or that people who see them have overactive imaginations? The former is impossible by physical and logical laws but the later certainly isn't. Hume said that no testimony is sufficient to explain a miracle unless the testimony is so compelling that its falsehood would be more miraculous than its truth. In other words, the more extraordinary a claim the more evidence is required to establish it. Hume also observed that when presented with new phenomena that it is more likely to be like something we already observed than something entirely new. When I was a lad scientists believed that tidal forces caused the same side of Mercury to face the sun all the time much like the same side of the Moon always faces the Earth due to tidal forces. Now we know that isn't true though its day is 2/3's as long as its year. No doubt there are many things we accept today that will be shown incorrect in the future.
The problem that you have is this: There is fiction, there is reality and there are lies. Lies are fiction that claim to be reality.
It is not always possible to figure out which is which. Historians basically do nothing but that. Puzzling which piece of information that they find is somebodys fiction, which piece is real and which piece is somebodys propaganda-lies about their enemy. Legends (like King Arthur) often have a true kernel and a lot of fiction spinning around that. Most legends exist in hundreds of different versions.
Same is true for fiction stories today. Vikings did exist. But there are also hundreds of fiction stories about fiction characters that resemble Vikings (and that may also be called Vikings in the stories) but that are not really equal to the true, historic Vikings.
No one can possibly answer your question about what things are real completely. Study history and all directions of science if you want it answered.
Magic for example does not exist. But there are a lot of things that can be explained today that people in former times believed to be magic.
And then, your question is pretty vague at some points. Greek Mythology is a set of stories and a religion. It did exist, in so far as the ancient Greek knew that set of stories and beliefs handed down that mythology over generations. It did exist in so far as that there was a group of people who actually worshipped those Gods and who had that religion. That mythology contained legends, some of which may have had had true kernels, and the ancient Greek believed it to be the truth. BUT You cannot possibly expect anyone to say that Zeus is a real God and lives on the Mountain Olympus in Greece. Or do you?