Ge 7:1 Then the LORD said to Noah, "Come into the ark, you and all your household, because I have seen that you are righteous before Me in this generation.

2 "You shall take with you seven each of every clean animal, a male and his female; two each of animals that are unclean, a male and his female;

3 "also seven each of birds of the air, male and female, to keep the species alive on the face of all the earth.

4 "For after seven more days I will cause it to rain on the earth forty days and forty nights, and I will destroy from the face of the earth all living things that I have made."

5  And Noah did according to all that the LORD commanded him.

At this point, Moses is teaching and encouraging his original Israelite readers obedience in learning to distinguish between clean and unclean animals. Just as righteous Noah distinguished between clean and unclean animals so must every single Israelite should.

Also, Moses is teaching them that their God alone has authority over all the living in the world including animals. He can dispose and preserve any of them at His will.

Many pagans back then worshiped animals, believing them to be deities. Moses shows them here the fallacy of that practice and belief.