So Seth, Eve’s son who essentially replaced Abel, seems to be the true inheritor of Adam’s legacy. Seth is first described as “in his [Adam’s] own likeness, in his image.” This, of course, parallels Adam’s relationship to God, making Seth the most God-like of Adam’s sons. This cyclical relationship—and the whole chapter—reinforces the theme of lineage and paternalism, and that passing on one’s likeness is of critical importance. Otherwise, you break the seemingly-infinite chain that eventually leads back to God. So yeah, it’s not just a cliché: according to the Bible, we are all literally children of God (if you go back far enough).