The Importance of Genesis 1-3

I'm trying to understand covenant theology. I'm reading Sacred Bond: Covenant Theology Explored by Michael G. Brown and Zach Keele. So far it is the best introduction I have seen written in this century on Covenant Theology. The book has a nice quote about the necessity of the Christian to understand the first three chapters of Genesis.

The apostolic preaching of the gospel is the bridge that brings us to God as Savior: it is paved and clearly marked. But the pillars on this bridge, which are rooted deep into the riverbed below, belong to Genesis 1-3. The streaming water may hide the pillars from our eyes at times; yet without the Genesis pillars, the gospel viaduct would begin crumbling beneath our feet, hurling us headfirst into the water.

Genesis 1-3 forms the essential foundation for the gospel, especially because it reveals the covenant of works. The doctrine of the covenant of works teaches us more about the perfect work of Christ and, in so doing, bolsters up our assurance salvation.(p. 42)

I'm not sure what the water(sin?) is in the metaphor and the metaphor seems strained, but the quote does stress that understanding Genesis 1-3 is key in understanding the full extent of the gospel.