Popeye's appearance is based on a fighter named Francis "Rocky" Fiegel that E.C. Segar used to know. Because of this, a tombstone was put on his hitherto unmarked grave in 1996. Segar paid Fiegel a small fee for the use of his likeness, as he was still alive when Popeye first appeared.
To ensure that people watched this short, it was marketed as a Betty Boop vehicle, and she makes a small cameo appearance in the movie. However, the main character is Popeye as suggested by the short's title.
When new animated Popeye cartoons were made by King Features in 1960 and 1961, the producers thought Bluto had been created for the Fleischer Studios shorts and that they didn't have the rights to the character, so they renamed him Brutus. (Bluto actually had appeared in a single adventure in the comic strip before any animated Popeye cartoons had been made.) The name Bluto was used again for certain animated Popeye cartoons after 1961.
In addition to Popeye being based on Rocky Fiegel, Olive Oyl and Wimpy also are based on real people. Wimpy is based both on E.C. Segar's former newspaper editor, Bill Schuschert, who was a great hamburger lover, and on an underhanded fight promoter whom Segar used to know. Olive Oyl was based on a schoolteacher named Dora Paskal, who was tall, wore her hair in a bun, and wore high-bottom boots just like Olive. She appeared in the comic strip Thimble Theater long before Popeye did. (Her original beau was a cowboy named Ham Gravy.)
Popeye originally appeared in a comic strip called "Thimble Theater" which was all about the Oyl family: Olive, Castor, Nanna, and Cole, as well as their friends. Castor was the main character in this strip. Popeye and his friend Barnacle Bill (not Bluto in his original incarnation but a Popeye lookalike) were both friends of Olive, Castor's sister. Popeye became so popular based on this that the whole comic strip was renamed after him, and eventually he started his own franchise with comics, cartoons, and feature films spanning from 1919 when Thimble Theater started until today. Olive Oyl starred in the Thimble Theater strip from 1919, while Popeye did not make an appearance until 1929. The Sea Hag actually predates Popeye in the strip and was his main antagonist for many years, not Bluto, who in fact only made one appearance in the comics. When the Popeye character was rebooted in the 1930s for the Max Fleischer and King Syndicate animated version, the show producers thought that Bluto was more of a suitable and appropriate villain for Popeye in what was conceived of as an action and adventure series with lots of fistfights. A female villain was not deemed as an appropriate foil for Popeye since they did not want to see him beat up a woman. As a result, the Sea Hag did not make an appearance until the 1960s King Syndicate animated reboot of Popeye. The way they resolved the dilemma in the 1960 reboot was to have Olive eat the Spinach and beat up the Sea Hag.