Best 2D platformer ever... or tied with DKC2 for the title.
Also, OP, let's not dismiss the first world as "just another jungle." There's so much variety packed into the Lost Mangroves -- and a mangrove is entirely different from a jungle! The way you swim between the tangled roots of waterlogged trees and then bop across dodos and past man-eating plants on sandy shoals, while Snowmad ships beach themselves in the foreground and spiraling trees burst out of the topsoil, before you skip across stranded subs, crashed planes and derelict ships that teeter and totter in tree branches... I love it! And the way the first world culminates in a "circus tent" actually repurposed from crashed cargo planes and canvas parachutes ties it together so nicely.
The freshest take on a tropical world in some time, and then you go to the second world, Autumn Heights, blending Bavaria and the Swiss Alps with a Canadian sawmill and Tibetan monasteries for good measure. Closet precedent there is the Northern Kremisphere from DKC3, and frankly that was a welcome motif to bring back since it's just not the type of place you typically associate with a tie-wearing gorilla and shuffling Viking penguins. Probably my favorite world, all things considered.