Step back for a second and look at the whole shape of it. Jordan Peterson's instinct about myth-weighted narrative is useful here, carefully applied: this story carries the psychological weight of catastrophe and renewal that shows up across nearly every ancient culture — Gilgamesh's Utnapishtim, the Atrahasis epic, flood memories from cultures with no contact with Mesopotamia at all. Lennox's approach to that overlap is worth adopting rather than being embarrassed by it: shared ancient memory of a real, catastrophic flood is exactly what you'd expect to find echoed, in distorted form, across many cultures, if something like this actually happened to the ancestors of peoples who later scattered and told their own versions of it. What's distinctive about Genesis isn't that it shares the memory — it's what it does with it. The Babylonian flood stories have squabbling, capricious gods, annoyed by human noise, saving one man practically by accident. Genesis has one God, grieving, just, and self-binding by oath at the end. Same catastrophic memory, entirely different theology laid over it.
And Lamin Sanneh's angle belongs here too, more than you'd first expect: this is a covenant made with "every living creature," with no ethnic or national boundary at all — the widest possible covenant in Scripture, centuries before Abraham narrows the promise down to one family in order to widen it again, deliberately, to all the families of the earth. The rainbow covenant is the first proof in the Bible that God's commitments were never meant to stay small. Everything Abraham's call will do in Genesis twelve, this flood account has already rehearsed in miniature — judgment, mercy, a remnant carried through water, and a promise stretched out over the whole earth rather than folded back into a single tribe.