I've programmed in a lot of different languages: BASIC, Pascal, Cobol, Fortran, WSL, C, perl, icon, and more. I've been paid to program in C, perl, Bourne shell, and others, but it turns out that the most important language I learned was one that I picked up on my own, to play with: Scheme.
Yeah.... Like Scheme did back in the '80s (except Scheme calls it "statically scoped"). Everybody keeps reinventing Lisp (and Scheme is just a specialized educational dialect of Lisp), but nobody's managed to do better than Lisp at so many things. The Evergreen guys are regularly doing sexy dynamic function creation stuff without even realizing that they've successfully recreated very-high-level programming methods that Guy Steele considered normal back in the early '80s.
Start by learning Common Lisp or Scheme, do some continuation-passing programming, and after that, everything new is just syntax.