Fantastic Fears
Fantastic Fears was an American comic book printed between 1953 and 1954 by Ajal-Farrex, which is now in the public domain, alongside most of its cast of characters.
It contained a mix of horror comics and more tangential adventure or superhero comics. Its publication history was complexed: its run started with an Issue #7 and Issue #8 whose numbering was carrying on from the earlier Captain Jet comic, which had a similar format but chose to advertise itself primarily on superheroes rather than horror. The third Fantastic Fears retroactively rebranded these as Issue #1 and Issue #2 by officially identifying itself as an Issue #3. This new numbering lasted until Issue #9, after which the comic changed names again to Fantastic Comics for Issue #10, and Samson for Issue #11.
Out of these, the “real” Issue #8 is the one of relevance to the extended Jenny Everywhere mythos, as it included Fear in the Jungle, a standalone comic story created by reskinning an earlier Jo-Jo the Congo King story, which introduced the jungle-hero Kaza. After falling into the public domain, a rebooted Kaza would go on to become one of the main characters of the long-running Jenny-adjacent webcomic Kaza's Mate, Gwenna.