What was the first CGI movie invented?

The first film to use cgi was metadata in 1971, but the first full-length cgi film was Final Fantasy: the spirits within

The first film to have all it's special effects cgi was "The Last Starfighter" (1984).

The first film to use all cgi (except for some cahracters) was "TRON" (by Disney) in 1982.

Tron was a combination of animation and CGI.