Not only the woman's son, the word used is "offspring".
3 [15] He will strike . . . at his heel: since the antecedent for he and his is the collective noun offspring, i.e., all the descendants of the woman, a more exact rendering of the sacred writer's words would be, "They will strike . . . at their heels." However, later theology saw in this passage more than unending hostility between snakes and men. The serpent was regarded as the devil (
Wisdom 2:24;
John 8:44;
Rev 12:9;
20:2), whose eventual defeat seems implied in the contrast between head and heel. Because "the Son of God appeared that he might destroy the works of the devil" (
1 John 3:8), the passage can be understood as the first promise of a Redeemer for fallen mankind. The woman's offspring then is primarily Jesus Christ.