One of the most enduring mysteries lingering in the background of Adventure Time’s rich world is what, exactly, happened to all the humans of the world? Finn was the only human in Ooo (with a few exceptions), but where did he come from, and how many others like him were there? Thankfully, the Islands miniseries answered that question — and Finn’s not alone.
Longtime viewers of the show know that the candy-filled, magical world of Ooo is actually Earth, centuries after a nuclear apocalypse known as the Mushroom War. This conflict killed most of the humans in the world, although a few well-known Adventure Time characters, like the Ice King and Marceline, lived through it (albeit as a wizard and vampire queen instead of as normal humans). While Ooo was rebuilding itself into the wild and lush fantasy land, a small group of human survivors fled to a distant island chain to rebuild society.
In the miniseries’s fifth episode, which focused on Susan Strong’s backstory, Dr. Gross sings a very nice explanation of the human’s history. Here’s an excerpt:
We had to leave our place because / The world was dying / And everyone that wasn’t dead / Spent all of their time crying / Our ways had failed nature had failed / We made a lot of errors / The Founders had some new ideas / That made everything better
Though we don’t learn much about the mysterious Founders, Gross’s song lets us know that the humans were creating a very rigid, somewhat dystopian society, with a rich caste system. Leaving the human islands was prohibited.
In other Islands episodes, we see that the humans tried to colonize other islands in different ways. Alva, the old woman with the bear that Finn met on the island with rapidly changing weather, was the last survivor of one such attempt. The virtual reality island was another apparent failure, and the island where Susan went to school in her flashback has since been abandoned.
When Finn meets his mother, Minerva (technically, when he meets his mom’s uploaded brain map), she explains that a deadly virus killed 62 percent of the remaining humans, which probably contributed to the run-down nature of some of their colonies. The humans appear to be consolidated on one main island, and when the series ends, it doesn’t seem like they want to leave to explore Ooo, though they have the option.
Although there are countless more humans alive than viewers previously knew about, there are still only a handful out exploring the world. There’s Finn, Susan, and her friend Frieda, along with a handful of other characters who may or may not qualify as humans. Finn’s uniqueness hasn’t been diminished all that much, but he certainly knows a lot more about himself than he did before his island-hopping adventure.