I will put hostility between you and the woman, and between your seed and her seed. He will strike your head, and you will strike his heel. (Genesis 3:15 HCSB)
The first prophecy was prophesied personally by God to the serpent. He told the serpent that his seed will be fatally injured by the woman's seed. The first prophecy developed on the theme of a redeemer or savior, on His one special characteristic - the seed of the woman. But this was way before God's covenant with Abraham (
Genesis 15:7-21,
Genesis 17:1-14) when the theme of king redeemer, people and land was more fully developed.
Seed of the woman
All men are descended from the seed of men. But God promised that there is a special man that would not be from the seed of man, but from the seed of woman.
If any man has a wife who became pregnant and it is not his seed, she must be an adulteress and had child by another man's seed. In Biblical times, both the adulterer and adulteress would be taken outside the city and be stoned to death.
At one point in history, this happened to a man. His wife was pregnant but it was not his seed. While he pondered over the next step to take, God intervened.
Now the birth of Jesus Christ took place in this way. When his mother Mary had been betrothed to Joseph, before they came together she was found to be with child from the Holy Spirit. And her husband Joseph, being a just man and unwilling to put her to shame, resolved to divorce her quietly. But as he considered these things, behold, an angel of the Lord appeared to him in a dream, saying, "Joseph, son of David, do not fear to take Mary as your wife, for that which is conceived in her is from the Holy Spirit. She will bear a son, and you shall call his name Jesus, for he will save his people from their sins." (Matthew 1:18-21 ESV)