the character Superman should enter the public domain is 2034
all the other characters in this Superman movie are way younger and therefore shouldn't enter the Public Domain until later
it's getting close enough to the date that Superman could become public Domain is the explanation of why all of these younger characters are being crammed into this movie (this is why Guy Gardner is the green lantern here, instead of Hal Jordan, Jordan's first appearance was October 59 but guy Gardner's first appearance wasn't until March 68, meaning that Guy Gardner shouldn't be able to become public domain until 9 years after the earliest year of Hal Jordan possibly becoming public domain) the Green Lantern Named John Stewart (the black guy Green Lantern) is a newer character than Guy Gardener (didn't appear until the DEC 71/Jan 72 issue of the green lantern comic) but he's not going to be the token black person in this movie because the Token black person in this movie is Micheal Holt who didn't appear until 1997 (and thus John Stewart is appearing as the black guy in https://en.wikipedia.org/wiki/Lanterns_(TV_series)
DC doesn't really want anyone to notice but they're really tripping about Superman and Batman becoming Public Domain soon