Noah was an almost-second-Adam who fathered an almost-new-humanity on an almost-new-earth. But his failure to break the curse and crush the serpent helps us understand what kind of a Saviour we really need to look for.
Abraham's story is not about Abraham. It's about God demonstrating His power by creating a great nation and bringing blessing the whole world, using only a nondescript 75-year-old and his childless wife.
Through the covenant with David, the whole storyline of the Bible converges and come together into one person, the son of David. He is the main character of the whole story, the one we’ve been waiting for all along.