Satan was still lurking around scheming to con man into giving up the authority which God gave him, Adam obviously did not take God instructions seriously when He said to subdue the Earth.
Satan who was a spirit entered the snake who was his most likely choice.
And it came to pass that the serpent who was the craftiest of creatures the Lord God had made said to the women, "If you eat the fruit from the center of the garden you will not die, but you will become like God, you will be as smart like Him, and you will know good from evil."
As a result of man's disobedience to God, Satan took the authority away from man and became the god of this world the planet Earth. I believe that it was God's plan to always give man a choice to exercise the free will that He gave us; God will always give us the opportunity to choice between good and evil, God and Satan. The fruit in the garden was the first, the choice between Jesus and Barbarous was the second and after Satan has been bound for a 1000 years and released will be the third. .
1John 5:19: We know that we are from God, and that the whole world is under the control of the evil one.
So they ate of the fruit, which God had forbidden them to eat, and so sinned against God. They immediately knew shame and covered themselves with fig leaves. God being a holy God could no longer have anything to do with them for they had broken their covenant with Him and as a result they were banished from the garden; when they died their souls would be condemned to hell.
The man and the woman now sinners were banished from the Garden, fell out of fellowship with God.
Man broke his covenant with man, but God kept His with man.
Geneses 3:15: And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shall bruise his heel.
A Savior will come through the woman and the relationship between man and God will be reestablished.
Therefore the address is not to Adam and Eve, but to Eve alone; and it was in consequence of this purpose of God that Jesus Christ was born of a virgin; this, and this alone, is what is implied in the promise of the seed of the woman bruising the head of the serpent. Jesus Christ died to put away sin by the sacrifice of himself, and to destroy him who had the power of death, that is, the devil. Thus he bruises his head - destroys his power and lordship over mankind, turning them from the power of Satan unto God;
Adam Clark Commentary
Acts 26:18: And Satan bruises his heel - God so ordered it, that the salvation of man could only be brought about by the death of Christ; and even the spiritual seed of our blessed Lord have the heel often bruised, as they suffer persecution, temptation, etc., which may be all that is intended by this part of the prophecy.
He made them to cultivate the soil from which they had been formed. How could a sinful man's soul have a relationship with a holy God? But man survived and multiplied but his nature was sinful and corrupt until God became increasingly disgusted with him. Satan tries to thwart God plan of salvation by having his fallen angles procreate with human women. Satan tries to contaminate the human race, so than God's plan of salvation will have to be aborted.
God had to destroy the Earth again by water, because of Satan's intervention.