There are quite similar stories to Noah and the Ark in ancient cultures all over the world....meaning: there are stories about a worldwide inundation in ancient times and various people who survived it by building boats or rafts and by finding high ground. The story about "Noah" is probably a story with a strictly local origin in one part of the Middle East, and it is probably symbolic of various survivors who rode out the flood, not just about the literal Noah and his immediate family. To take the story absolutely literally as it is written in the Bible and to thereby discount all the other ancient Great Flood survivor stories from so many other cultures is to base one's belief upon ignorance, willful or otherwise.

There are a great many animal species which would certainly not have been found at all in Noah's part of the world, and they also survived whatever happened, so Noah quite clearly would not have been instrumental in saving those species even if he saved some animals.

The story is probably symbolic of many different people who survived in many different places........a parable, in other words, not a literal tale of what happened.

North American Indians had ancient tales about a Great Flood too, and those tales mentioned some wise or heroic people who survived it by building boats or rafts and by getting to high ground. They were NOT talking about Noah! They were talking about other people in their own part of the world.

To think that the Noah story is the only story to be told about this event is, frankly, ridiculous....but people in any given culture in this world normally believe what they've been told in that culture providing they haven't heard any alternatives to it....and that has been the case with most Christians, Muslims, and Jews for the past few centuries. They were told about Noah. They were not told about all the other similar tales from other cultures and traditions.

What could have caused such a flood? A major change in the Earth's climate or the Earth's atmosphere, that's what...even a huge astronomical event like the passing of another large body in space affecting the Earth. And it may have been something that lasted a longer time and happened more gradually than is told in the Bible account.