TCG historians argue about the "first TCG." Many credit The Base Ball Card Game (1904) or Magic (1993). Card En Ciel sits in a weird limbo—it is arguably the first "anime-style" TCG and one of the first to use randomized booster packs.
The truth likely lies in the middle. While mass-produced "rainbow" variants of modern sets may lose value once the hype dies, are likely to become heirlooms. They represent a moment in printing history where an accident became an art form. Card En Ciel