It's well known the game's first few worlds are fairly straight forward and generic. I love SM3D World but also felt the game was a bit underwhelming at first. But it ramps up, so don't be put off by that. The first few worlds are designed for kids on purpose, no big deal, the game is also biiiig, so don't worry that half the game is non-content, it isn't.
It's a normal complaint about the game, it gets better, don't worry.