Genesis is about beginnings: creation, the origin of species, the inception of man, the birth of nations, and the dawn of salvation history. In the content it expresses, Genesis is unique among biblical books yet is an integral part of the entire Christian canon in the foundational function it provides.
Genesis derived its name from the Greek translators who attempted to define the content of the book from the frequent use of the Hebrew word toledoth, most commonly translated “generations.” The ancient Hebrews simply took the first word of the book to designate the title of the book. Hence it was called bereshith, or “In the beginning.” Either way, whether by using toledoth or bereshith, the book is well named. It is a book of cosmological, national, and theological beginnings, setting the stage for the continuing drama of God's dealing with humankind and, in particular, his dealing with the people of Israel. It thereby introduces us to the earliest ancestors of the nation and their emergence from the ancient Near Eastern milieu in which they originated to become the forefathers of a chosen race.
Genesis makes clear the fact that the Israelites were not a different race of people per se, but simply a chosen race based on a spiritual distinctiveness as opposed to an a priori national consciousness or physical uniqueness. They continued to be related to the peoples and tribes of nations that surrounded them. It is through the stories of the Israelite patriarchs described in ch. 12 and following that the consciousness is born of a people with a special mission and destiny in the world.
Genesis, therefore, is primarily theological history. It depicts the unfolding saga of a God who makes and keeps covenants with the progenitors of a nation. Israel's theological distinctiveness, then, is closely allied with the concept of covenant. When that is lost, there is nothing. When that is retained, Israel's uniqueness as a chosen race remains.