After the Tower of Babel, humanity had again lost the plot of living as God's people in God's place under God's rule, receiving God's blessing. So God essentially rebooted the storyline with one childless seventy five year old pagan man named Abram. If he trusted and obeyed God, God would make him into a great nation, give him a promised land, and bless all the peoples of the earth through him. Where Abram and his offspring doubted, feared, and failed, Jesus ultimately fulfilled the promises of this covenant.