The Watchers, Nephilim, and Noah's Ark

Enoch warned the Giants and the Watchers of the world. Repent or feel God's wrath.
They ignored his warning.
The floodgates of Heaven burst forth and water rushed over the Earth, destroying everything. 
The only thing to survive is a single vessel, a huge ship: the Ark. 
5 months later, the waters receded and the Ark made ground on a mountaintop. A man named Noah emerged, and civilization began again.
Some version of the Noah's Ark story exists in almost every religion and every culture on Earth.
But did Noah and the Ark really exist?
There's evidence that they did.
So much evidence, that it was classified by the CIA for almost 50 years.
But why classify it? Well, there are two problems with the Noah's Ark story. One, the Ark is much older than anyone thought. And two, the man named Noah? He wasn't a man. At least, not a man from Earth.