(Genesis 9: 12 And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations: 13 I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. 14 And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud: 15 And I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh. 16 And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth. 17 and God said unto Noah, This is the token of the covenant, which I have established between me and all flesh that is upon the earth.).
God blessed Noah and his sons and told them to multiply and replenish the earth.
The cleansing of the evil from the earth is also a shadow of the reality of Baptism as we enter into a covenant with God through His son, Jesus, and as Noah did everything God commanded him, if we do everything God commands us to do, then Jesus becomes our Ark of safety (and as God "shut" Noah into the Ark, He "shuts" us in or "adds us" to His church). But we do not "wash" ourselves because we are "dirty", but because we answer the call of God to cleanse our conscience.
(1 Peter 3:18-22 "For Jesus Christ also died for sins once for all, the just for the unjust, in order that He might bring us to God, having been put to death in the flesh, but made alive in the spirit; in which also He went and made proclamation to the spirits now in prison, who once were disobedient, when the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is 8 souls were brought safely through the water. And corresponding to that, baptism now saves you, not the removal of dirt from the flesh, but an appeal to God for a good conscience, through the resurrection of Jesus Christ, who is at the right hand of God, having gone into heaven, after angels and authorities and powers had been subjected to Him.") and (Romans 6: 3-7 "Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. For he that is dead is freed from sin.")
It is that man who, through faith, "calls" upon God that will receive the promise that is in Jesus Christ. And it is that man who then walks circumspectly in the paths of righteousness that will receive his crown of glory in eternity.
(Galatians 3:22-27 But the Scripture has shut up all men under sin, that the promise by faith in Jesus Christ might be given to those who believe. But before faith came, we were kept in custody under the law, being shut up to the faith which was later to be revealed. Therefore the Law has become our tutor to lead us to Christ, that we may be justified by faith. But now that faith has come, we are no longer under a tutor. For you are all sons of God through faith in Christ Jesus. For all of you who were baptized into Christ have clothed yourselves with Christ.)
It was Christ's blood that was shed that our nakedness (sins) might be covered. As was the blood of the perfect lambs of the flocks chosen for the first Passover and placed on the door-jambs, it is the blood of the Lamb of God, sprinkled on our "door", which death passes by.
The plan that God made to bring man back to Him now begins to unfold. He had shown man that by man's obedience to God pleased Him. Enoch walked with God, and was no more for God took him. Noah obeyed divine commands and he and his family were preserved from the flood waters in the Ark. Now was the time to prepare the family that would become the Messianic Nation. This would be the family into which Jesus would be born, and Jesus was to be the Messiah, or Savior, of the lost world.