The Bible does not set itself up to be a physics book or a biology book. It tells the truth to people in a way that they can understand. The important truth about the creation story is that God created the universe and all life in it. Man was created in the image of God (i.e., has a soul) and man rebelled against God bringing sin.
The Flood story probably records a flood that actually happened early in human history since virtually every culture has a variant. But the main purpose of the Flood story is to teach us that God will save those who are obedient to His will.