Melee added Fire Emblem before any Fire Emblem game had been released outside Japan.
Super Smash Bros. Melee introduced two fighters from the series, Marth and Roy, to an international audience in 2001. At the time, Fire Emblem was a long-running Japanese strategy-RPG franchise, but its games had not received official releases in North America or Europe. For many Western players, Melee was their first exposure to the name and characters.
That crossover appearance helped raise awareness of the franchise beyond Japan. Nintendo later released the Game Boy Advance title Fire Emblem in North America in 2003 and Europe in 2004. It was the first game in the series officially localized for those regions, although it was not marketed with a numbered subtitle in the West.
The other options were already established internationally through Nintendo franchises with overseas releases: Metroid, Star Fox, and F-Zero. The wording refers to the franchise's games, not to whether the individual characters had appeared in another form. Marth and Roy's presence in Melee came before Fire Emblem's Western debut.