(Forward-pattern; each later Luffy-vs-villain captain-validity adjudication scene re-keys the prototype. Pending Alabasta / Enies Lobby / Dressrosa / Wano payoffs.)
Earliest known caller
(Pending — first verbalized by Luffy at Ch. 90.)
Why this matters
The captain-validity-adjudication prototype is a Luffy-signature combat-frame: when a tier-villain asks Luffy what gives you the right to be captain?, Luffy answers I can beat you (single-clause, operational, not philosophical). The pattern is doctrinally-symmetric with Ch. 63’s place-to-die declarative — together they constitute Luffy’s two-axis villain-rhetoric-rebuttal grammar.