Nope, believe it or not the first Metroidvania style game was Castlevania 2: Simon’s Quest for the NES. It was actually an excellent game, but a botched translation to English made it more frustrating and obtuse than it should have been. It was rather ambitious for a NES game.

Also, while level based and not Metroidvania style, Castlevania 3, Super Castlevania IV, Bloodlines, and Rondo of Blood were all fantastic games and Iga’s games have their lore and continuity based on the prior titles.

Not to mention, while it wasn’t as well received, the attempted series reboot (Lords of Shadow) was pretty great too. Mostly people didn’t like the gameplay changes for the 3D title.

And that’s not even getting into the N64 and PS2 games (one of which, Curse of Darkness, was popular enough that the first Netflix Castlevania series involves characters based on it).

Metroidvania was Igarashi’s style, to the point they were sometimes coined as “Igavania” games, but they’re not the end-all-be-all of the series.