The poem is built from fragments that seem to come from a single stunned thought. It opens with a hunter who would not be "wooed by lions," an odd phrase that turns the hunted animals into something seductive, something that might call a person toward them. The title, "Nimrod," is a name often tied to hunting, so we can read the figure as a hunter who turns away from that pull.
The speaker then admits surprise: they never imagined anyone on earth could be "so little curious." That sounds like both astonishment and mild reproach. How could someone ignore the wonder in front of them?
The last line gives the answer, or perhaps the verdict: "the world is all cards and ash." Cards suggest games and chance, ash suggests what is left after burning. Together they make a world that feels flat and used up. The mood is bleak and a little puzzled, as if the speaker is describing a kind of numbness, and perhaps half-recognizing it in themselves.