Yes, God chooses us. Yes, God chooses a lot of unlikely people. Abraham and Sarah, for example. They were old, really old--100 and 90--when God told them that they were going to have multitudes of descendants.
But, notice that Abraham and Sarah didn't just sit idly by waiting for the future to fall on them. Because of their faith, they were able to respond rightfully.
These great ancestors of ours lived in a way that demonstrated that they really believed that God delivers on promises.
(Caveat: those of you who have read ahead know that Abraham and Sarah sometimes slipped up.)