PL1 is approximately 54, and it was put together to cover the application domains of 2 previous language successes, Fortran and COBOL, which still live. Fortran is more than twice 30 years old, BASIC approximately 53, RPG 59.
Haskell is the youngest language that isn’t derivative.Monads for IO weren’t being seriously used until the late 90s. All the imperative C derivative languages are much older.
A very young language that is (to my knowledge) not derivative of older ones unless you count Excel: https://www.luna-lang.org
It comes with C, JS, and Haskell interoperability, and it's implemented in Haskell, but the heart of the language is its visual representation. I have personally never seen anything like it before.