Post-apocalyptic back ground - The Great Mushroom War

Hello everyone!
Just want to say, Finn, he's suposadly the only human left on Ooo. But why is that? In some episodes you see random war debris everywhere E.g. in the opening title screen of the song (you know what i mean) right at the beginning the are nucular bomb shells stuck in the ground. And in one of the episodes Jake and Finn are talking about rockets and Jake says, 'Rockets haven't been re-invented yet.' I think the whole back ground story of adventure time is that, the humans went into a huge war that was pretty much like Armageddon (just in war form) and that ice king, or Simon, protected Marciline (the episode were he is letting her younger form ride on his back and chizz) they were both humans at the time and he protected her using the crown. However, Finn also survived this (i don't know how yet) but he did and afterwards, Finn tryed to forget everything that happened (so... put a block in his mind) and forgot. Then he was found by Jake and his family and raised by them. Marciline was then turned into a vampire and so forth and lived till the present day (sometime in the 3000)
Your probably wondering what my point is. Well, all that random carp you just see lying everywhere is actually war materials and chizz. Finn survived a huge war that ened the war and then the world just started again E.g. Princess Bubblegum she a human/bubblegum hybrid, therefore a mutation. All of the Candy people are just mutations from the debris of the war.
Please say what you think!
Bye!!!!      MATHEMATICAL!