I'm Not the Main Character!

After saving a girl and getting hit by a car, I was reborn as Rex, the strongest early-game character in an RPG world! My starting level is an astounding 50! I possess skills in every field, and to top it off, I'm handsome! This is a huge win!... Or so I thought. Rex is a rescue character in the early game. Like an initial SR card in a social game or an old paladin with a silver spear in an SRPG, I can only dominate at the beginning before becoming useless! Facing monsters and events that keep attacking me, my abysmally low growth rate, my disappointing unique skills, and my frustratingly versatile stats, I made a decision. "I'll leave the troublesome matters to the main character who should be somewhere, and retire early!" This is the story of an ordinary person who "finds the main character" and somehow becomes a hero who saves the world.