I will put enmity between you and the woman, and between your offspring and her offspring; He shall bruise your head, and you shall bruise his Heel.” (Genesis 3:15 ESV)
Human
While the second person of the Trinity was active in Creation, it was not until after Adam’s Sin that we learn that something even more amazing was going to happen.
The Messiah would be human, as well as divine.
Particularly, the Incarnation would literally be Infinite God being born to a finite woman.
This was necessary because victory over Sin only is possible if the Messiah was both God (perfect, and without limits), and human (part of creation, potentially fallible, and therefor truly innocent).
God’s threat to the serpent was surprising and confusing, no doubt. But years later, it became clear.
Christians are not saved by emotions, general healing of the broken, or God being nice. We are saved through Jesus, perfectly divine and perfectly human.
And that was announced first immediately after the Garden.