Though Lois and others were one-off Superwomen in the '40s and '50s, the true inspiration of Supergirl is Mary Marvel. Superman's 1940s rival, Captain Marvel, had stronger stories, better artists, and a more realized family and mythos in his wildly successful run; writer Otto Binder and artist Marc Swayze created his sister Mary Marvel (1942), a sweet and positive teenage powerhouse as formidable as Wonder Woman. After the jealous DC sued better-selling Fawcett Comics out of business, they assimilated their staff and concepts; Superman in the '50s gained a super-family of titles with a cohesive mythos, a Silver Age revival built from the Golden Age of the Marvel Family. Writer Otto Binder himself, with artist Al Plastino, reinvented his Mary as Kara, the teenage Supergirl who brought light and youth to Superman's world (1959).
Rocked by the failure of Superman III, the producers hit refresh with this 1984 film version of his sunny cousin. Expectiatons were high for a return to the magic of the first film, but it was received with uniform disappointment. Many of its wrong moves come from relying on gender and teen cliches. As if assuming Sci-Fi was too boyland, the opening goes for a percieved girl-friendly Fantasy approach to Argo City that rings odd, along with the magic angle for the villain. The key discernment here may be to stop expecting a Donner-style adult film of wonder, and to realize it's a formula Disney movie for kids; in film style, plot contortions, expedient illogic, and character tone it could be any Disney film for youth, whether 1964 or 1974. This is why adult fans dismissed it but impressionable youth enjoyed and still champion it.
The brightest aspect of the film is Helen Slater, who really does personify the radiant hope of Kara. This is truest in the flying sequences, whether by wire or opticals, which convey the angelic spirit of the Supergirl we love.