>>104390437Before she was Captain Marvel, there was another Captain Marvel. He was a Kree who came to Earth and decided to stay, and he died a hero and a legend. His powers were partially transferred to Carol by an Omni-wave device accident.
Due to another accident Captain Marvel became trapped in the Negative Zone. When he touched his Nega-Bands together he changed places with young Rick Jones, adventurer and sometime companion of the incredible Hulk, and Rick was sent to the Negative Zone in his place.
>>104390317Shazam was the name of the wizard who gave the original Captain Marvel's powers to a boy named Billy Batson in the Fawcett Comics publication, "Whiz Comics". That publisher is defunct and its characters are no longer in circulation.
A conceptually identical character has been owned by DC Comics since 1972, but this character is called Shazam, and got his powers from a wizard.
Another conceptually identical character is Marvelman, who was first published in the UK after DC Comics forced Fawcett Comics out of business in 1953. Marvelman was created to fill demand for stories about Captain Marvel, who had been very popular reprint material for the UK market until then. He continued in print from 1954 until 1963, at which point his rights reverted to his legal creator, Mick Anglo. Anglo never read his original contract and so was unable to prevent several other versions of his works being created, until Todd McFarlane claimed to own them and as part of a separate legal dispute it was discovered by Neil Gaiman that Anglo had owned the whole rights since 1963. McFarlane lost all claim, the various creators of the knockoff versions agreed to transfer their royalties to Anglo as a sign of solidarity, and Marvelman/Miracleman was sold to Marvel Comics, owners of Captain Marvel.