The word “seed” is used six times in Genesis 1, twice each in verses 11, 12, and 29.  None of these refers to a human being.  The first use of the word for a human being comes in 3:15, which is the next time the word is used after chapter 1.  Again the word is doubled: “enmity between your seed and her seed .”

The distinction and analogy between “seed” and “seed” is important.  Fruit trees bearing seed are types of men - or, better, women - bearing seed.

The numerology is important too.  The seventh use of the word is a reference to the seed of the serpent.  As the seventh seed, he owns the first week of human history.  But there’s another seed coming, “her seed,” the seed of the woman, the eighth seed who begins a new week.

The next time the word is used in Genesis is 4:25, to describe Seth.  Neither Cain nor Abel is “seed.”   But Seth is, and specifically he is a seed appointed by God, to replace Abel, the second second-born.