Accounts of the Flood are contained in both the Gilgamesh Epic and:?

The epic also talks of ogres, and a giant raised by a Sun God, amongst other things. Gilgamesh is an epic poem and is no way a reliable sauce, and neither are any of the other texts you mentioned. Flood myths have been around for many thousands of years, since the beginning of civilisation. But so have myths of dragons and ghosts - it doesn't necessarily mean they are real. Early humans had a great connection with water and the ocean and sea's of the world, both for food as well as travel. Of course, myths would arise about the ocean and apparent floods.