God made promises to Abraham (Gen.12:1-3, 17:7) & his’ Descendant/The Seed‘ (Christ, the Messiah), but the Jews stumbled on this (Isaiah 28:16, Rom. 9:33), they misinterpreted it & took it as it was just for all Abraham’s descendants in the flesh, Israelites. Sadly many Jews still believe that today!
In the Old Testament the Hebrew word H2233 Zera, = “seed” is a singular noun that can also mean offspring. Many modern bibles translate or change the Hebrew word “seed” as “descendants,” “children,” (plural only). This makes it even more difficult to understand, altering the scriptures & the doctrine. To know if ‘seed’ has singular or plural meaning we need to read in context. In Greek there are distinct words for seed (spermati) & seeds (spermasin).
In Gen.3:15 & 4:25 said “and I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.” & 4: “25 And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew.” These passages are using the word seed as singular, for one person alone.
Same in 2 Samuel 7:12 God’s word to King David “And when thy days be fulfilled, and thou shalt sleep with thy fathers, I will set up thy seed after thee, which shall proceed out of thy bowels, and I will establish his kingdom. 13 He shall build an house for my name, and I will stablish the throne of his kingdom for ever.”