Issues from the mid-1960s that simply pitted characters against each other were common, and it makes sense. During a formative time, everyone wanted to know who were the best, strongest, brightest, etc. It’s the classic comic book argument.
The issue starts with some kids arguing about is stronger. Thor arrives and tells them the story of Avengers #3. Where Hulk and Thor argued about who is stronger. They they threw punches.
Thor is the narrator, so of course he wins. Bob Harras and Jackson Guice paid tribute to this terrific issue in Thor #356, only there the tale is told by Hercules, and it is he who bests Thor.
Also in this story, Thor tells us that Hulk actually gets stronger the more he fights. I’m pretty sure that’s new information for readers–don’t think that’s been part of the lore before–and we see Hulk lift Thor’s hammer!
…But it was only because Odin disenchanted it, so that Thor could fistfight Hulk without reverting to his Donald Blake form. Once it is re-enchanted…
The “Tales of Asgard” backup has the origin of Loki. It’s brief. He was too short to be a giant so Odin adopted him. Boom. Resentment formed at a young age!