Did mythical Creatures/beast ever exist

Did mythical creatures/being exists or still do exists. 

Did those stories (now regarded has a myths/legends) ever happened.
I think they did.
When I think about ancient myths/legends......., were people so smart enough to make up a mythical creature story, or any story that was not true, that lasted a few thousand years.... 
Yes OK, maybe somebody made a false story up, but them stories are forgotten with in a few decades. 
The only reason I can think, of those stories/myths of lasting Milena after Milena is, them stories/myths were true OR based around a true event
For instance I am living in 5000BC, I, like every other people, work very hard every day to make a scratch of living.. There is no time at all to be day dreaming in any way, of mythical creature, or tell a story about mythical events. I believe the minds in them days were way to fickle to understand fully what happens in them days.

I mean people from thousands of years back didn’t have the resources or knowledge to make up such mythical creatures/stories, unless they saw it, or saw something similar to it.
Even today people are discovering new creature so weird that we presume it is from outta space, or looks so similar to a mythical creature from the books.

People today can make up creatures/beings, because we see them everyday, in television, books, Internet and so on.
But even in the early days of television, the creatures/monsters we see on television everyday, are some what based on creatures we see in the mythology books.

I like to give you people a example:s 
1. Medusa... Now when I look at Medusa, I see a huge snake swallowing a human female, from legs up.. Also that females hair was long with dread locks. But I cannot begin to guess how Medusa made men into stone...
Maybe its a severe case of F.O.P -  Fibrodysplasia Ossificans Progressiva., 
2. Over the centuries, we have heard about babies being born with multiple limbs. One of the most recent and famous was a girl named Lakshmi Tatma, who had 4 arms and hands and 4 legs and feet's. By looking at this baby, it got me thinking about the myths, goddesses/deities, especially from the south Asia legends. Perhaps some one was born in that region, tens of thousands years ago, in the same way Lakshmi Tatma did, and survives into her adult hood. Because of this miracle, they named that person a goddess.
With these two examples, I believe all stories in the ancient times is some what true, with a bit of logic and common sense, we can decode them easily.