Genesis 12:1–15:6 focuses on one man, Abraham, who is part of the fulfillment of the promise God made in the Garden to redeem humanity. Abraham must do two things: believe, and act on that belief. When he does, God makes an eternal covenant with him and with all his descendants, Israel and the church. We too must follow the pattern of our father: believe, and act on that belief.
The authors of the New Testament refer to Abraham as the person with whom God made the covenant as the father of the nation of Israel. At the time God established the covenant, the man's name was Abram. God changed it later to Abraham and that's how he is referred to in subsequent references.