What characterizes the short toledoth at Gen 11:10-26?

Also, what is its function? Was it really necessary? What do the genealogy and years lived imply about the faith of Abram? The toledoth recounts “the generations of Shem”—the originator of the Semites—and we must bear in mind that it is not first and foremost about Shem himself but his family, or descendants. So this connects Shem, Noah’s son, with Abram, the focus of the next great narrative. Noah was blessed, and he passed on that blessing explicitly to Shem (Gen 9:26-27) and his line. The promise of Shem, and by extension the promise of the “seed” (3:15), passed on through this line ultimately to Abram. That is the main point. The genealogy also illustrates two facts, one already announced—that the span of man’s life would be 120 years (6:3)—and one more obscure—that the first five generations from Noah were alive, if not on hand, even into the time of Abram. This further entails that a living memory survived to Abram’s time not only of the Lord, but of the sacrifice and God’s covenant, of the Flood and its reason, and of evil, antediluvian days. Unless the families were utterly separated, which is quite possible, or lost touch with the old faith, which is also possible, the memory of the Lord and of sacrifice would not have to be wholly renewed in Abram.