As Lehi recounts the story of humankind’s beginnings, he emphasized the choice and the fact that they made that choice in the face of opposition. The point was that the choice was made, and the role of the Satan in the process was incidental.
The result of the choice was the beginning of humanity as we know it. They were driven from the Garden and began the necessities of life. They tilled the ground in order to bring forth and support life. They brought forth children who became “all of the inhabitants” of the Earth. They began to put God’s plan into effect.
There was still the lingering problem resulting from eating the fruit. Our choices have consequences, and this primordial choice had the consequence of mortality. To further the ability of humankind to properly develop the attributes of heaven, God gave them laws. Importantly, along with the law was the possibility of repentance. That there would be a need for repentance was virtually a given. The fact that repentance was possible was the result of God’s grace. All humankind was in a position where its actions might separate it from God’s influence, perhaps similar to how the angel who became the devil was separated from God’s influence. That undesired effect required remedy, and repentance was the remedy. That repentance is available only through the Messiah’s redeeming sacrifice. Lehi is leading up to that explanation, but he has more to say about our mortal condition before he does.