Hm, iirc, Waddle Dee's were in cages, and the gorilla guy had a cage with some around his neck, so I'm guessing he's a servant of the main antagonist?
I think the story is that Kirby and his friends wandered into the Forgotten Land and were attacked and captured by the antagonist, and so now it's up to Kirby to save them. Maybe the antagonist is an ancient being who is against modern-world people intruding in their lands?