Actually the character is purposely just a white ball. You're supposed to find out why after beating the game without dying, but I've realized that it's pretty difficult to do that. For the descending metal bar, you're supposed to let the bar drop all the way to the bottom and collect the key when the moving sawblade reaches the very edge. Then you have to quickly go around and get back onto the metal bar before it rises back up again. This level turns out to be the trickiest of them all.
Thanks for reviewing :)