Why there is no simple first frigate

What was the first class of ship to be called a frigate?

There is no clean first class because the term and the frigate-built hull form evolved gradually, with important Dutch roots.

English sources described ships as frigate-built before the category hardened into a standard rating. The word itself also points toward Dutch usage and an earlier design tradition. Because name, construction, and operational role changed at different speeds, no single launch cleanly creates the type. Later warship categories should not be treated as if they appeared fully formed.