Who knows?

Why does everyone have the same image of unknown creatures appearances? I believe we have the same ideas because stories and media have shown us pictures. We are told how they look, and all stories follow each other. I'm sure people have thought they seen a creature and wrote a story, when someone else writes a story they just follow the information they have been fed. Media and stories, old and new cause us to imagine the unknown as we do. Who was first to create the stories of aliens and sasquatches? Some people have said that there was drawings in caves of extraterrestrial like beings that have antenna. These may have been drawn as far back as 8000 bc. The first major alien sighting was in Roswell new mexico in 1947. There was even alien corpses found. If true the first sighting of the sasquatch would have been in 1955. A man seen a female sasquatch in the Rockie mountains.