"A little that the righteous have is better than the abundance of many wicked" (Psalm 37:16). The rabbis of Aggadat Bereshit loved this verse because it turned ordinary logic on its head. The wicked had multiplied. The nations were seventy — a myriad of peoples spreading across the post-flood world. And into all that multiplicity stepped three men and their wives from one ark.
Noah's sons — Shem, Ham, and Japheth — went forth from the ark (Genesis 9:18) into a world that needed repopulating. But the rabbis were more interested in lineage than in numbers. From Shem came Abraham. From Abraham came Isaac. From Isaac came Jacob. From Jacob came the twelve tribes. The entire promise to the patriarchs was already implicit in that first "went forth" — a small group, bearing something that no amount of Gentile abundance could dilute.
This is the paradox the midrash savors: Israel was chosen not because it was large. God Himself said so — "Not because you are the most numerous of peoples" (Deuteronomy 7:7). Israel was a little that the righteous had. And the nations, for all their armies and territories and civilizations, were the abundance of the wicked — a wealth that would not outlast its own emptiness. The ark had contained everything the world needed to begin again. And what it carried was not many. It was specific.