Why do you think so many of our ancient highly advanced ancestors from all over the globe...?

...took so much trouble and care to record and display numerous characters and events in their writings, art and buildings that were merely myths and fairy tales, as opposed to actual events and characters of their time? Why do you think so many have dismissed these ancient depictions (Greek mythology, Indian, Sumerian/Biblical, Peruvian, Chinese, etc.) as fiction, when they could very well be facts? A lot of angel/alien beings, orbs and ufo's were described then, and many people since then up to today claim to see similar things. Could so many people of the past and present all be "crazy"?