The human race can be divided into two classes: the godly who listen to God and the ungodly who reject God.
Genesis 6:14 BDC: How could the ark have held all those kinds of animals?
It is important to note that the account of the Ark and the flood in the Book of Genesis is an account from the Hebrew Bible. Its purpose is not necessarily to provide a scientific explanation of events. Nevertheless, there are many reasonable answers to this question.