That's a fun question! There isn't a single "first" Jesus Christ Superstar in the literal sense. The title "Jesus Christ Superstar" refers to the rock opera created by Andrew Lloyd Webber (music) and Tim Rice (lyrics).
So, instead of a single person, it's more accurate to say that:
* Ian Gillan (of Deep Purple) was the first person to sing the role of Jesus on the original concept album released in 1970.
* Jeff Fenholt was the first person to play the role of Jesus in the original Broadway production which opened in 1971.
* Ted Neeley and Carl Anderson are both considered stars of the 1973 film adaptation.