The common factor that we see in the Torah is known as the tikun ha'shrashim and this is the essence of the history of the entire Torah. When Adam was created, he was created to do his avoda, to be mishtadel of the mitzvos, and to merit the World to Come. Adam was the type of soul that whatever he did not only affected him but everyone that came after him, because all souls come from Adam. For this reason he was called a shoresh or a root. His actions of mitzvah or sin can influence the purpose of all souls after him. When Adam failed, that purpose was given over to Avraham, Yitzchak, and Yaakov and their descendants.