So, for quite some time, I've had a crazy theory: DKC is after the apoclypse. Of course, I look for traces of after-the-end possibilities in everything, so it's not crazy I did so in one of my favorite series. Here are some of my ideas:
People have always said that monkeys evolved into humans. I always thought such things as baloney, but anything is possible in a video game. OK, take a human. Then, add fur and other things that make him look like a monkey, and add agility plus ape instincts. You now have a Kong... But what about Kremlings? I belive they were also devolved from humans, but something went wrong - they turned into crocodile/aligators instead. Luckily, they still had sentientness and some other human charisticts, so it wasn't all that bad.
Now, how did these things happen, exactly? I belive some steriotypical scientist decided to add the good things of humans and apes together, creating the first Kong. After doing some expiriments, they created a Kremling and some of those other creatures from the Rareverse. They thought that since it was so great, they should do it on the entire world! But, somepeople wouldn't know how good it was until it happened to them. The solution? Bomb everything with some Kong-creating goo! This also creates Mushroom Kingdom stuff, ect.
Of course, that still leaves DK's circus antics to have. I think that all those happened with a regular monkey named DK, and some random dude named Mario. As the scientists started tested, they accidently poured some stuff down the sink, so some of the sewer stuff got mutated, so that random guy and his bro had to clean it up.
Then, after the bombing, the mutated Kong family found a game based off those adventures and acted like they were their lives, with Cranky even recreating DK Jr. so DK thought he was the namesake. Then, the Kremlings arrived and used their intelligence to ramake all the structures on the island look like they created them, and took over the factory.
From then on, the Kongs found more evidence of the past, unaware of how they were really created.