Ancient Near Eastern conquest accounts routinely use sweeping, stereotyped language; “I left no survivor,” “I destroyed them utterly”, as standard rhetoric of total victory, even when the records show the enemy very much alive afterward. Scripture shows the same pattern internally: Joshua says whole regions were “utterly destroyed,” yet Judges 1–3 has those same peoples still numerous and needing to be driven out. “Men and women, young and old” reads in this setting as a merism for everyone in the stronghold, and the targets (Jericho, Ai, Hazor) were fortified royal-military centers, not nurseries.
This is not a convenient escape hatch; it is reading the text as its first audience would. Hold it modestly. The point is not that no one died, but that the language is hyperbolic battle-report, not a literal census of slaughtered toddlers. The conquest was real and severe; it was also described in the idiom of its age.