Allegory is a tricky business. I'm not sure it would have been a good idea for ROCKET ROBIN HOOD to hang out with the Robin Hood of legend--they might compare notes and realize how oddly similar their worlds were. But maybe Americans don't know about ROCKET ROBIN HOOD (it was a Canadian cartoon show, I used to watch religiously--but maybe folks in the States never saw it).
Well, how about Quality's Joe Hercules--who debuted in HIT COMICS No. 1 (July '40)? "He didn't come from another planet . . . he wasn't made by a mad scientist or by some other fantastic manner . . . He's a real American youth, born in the north woods and imbued with the greatest strength mortal man ever possessed . . . " There's an obvious allegory to the Hercules of myth, but I think that analogy would fall apart if mythic Hercules entered the picture.
Superman was created to be like Samson, Hercules, Moses--but in an allegorical way--not in the genuine way that Captain Marvel got his powers from Hercules, Solomon, Atlas and their buddies.
Once Superman was an established legend in his own right, he did meet up with Hercules and Samson, but by that time Superman was the most popular super-hero in the world. Moreover, the mythic world in the Superman universe was specific to that universe. Superman had his own version of Atlantis and Amazons that were different from what was seen in Aquaman and Wonder Woman stories. The Hercules and Circe in the '60s Superman adventures were supporting characters of his mythology. He wasn't a supporting character in theirs.
Jack Kirby's Fourth World is an odd Super-Duck. There's an intentional clash of motifs in this Kirby work. Mash-ups of science and myth, ancient symbols and modern symbols. A lot of the energy is drawn from that weird juxtapositioniing. Orion is named after the original Orion--is he meant to be a reincarnation? There are characters named Lightray, Amazing Grace, Fastbak, Mark Moonrider, Desaad, Steppenwolf. It's hard to figure out how we're supposed to read this allegory.
I think the Fourth World has always had an uncomfortable position in the DCU, because it works according to a different set of rules. It doesn't easily fit either into the science fiction worlds of Superman and Green Lantern or in the mythical worlds of Wonder Woman and the Sandman.