A start
Alright. I can definetly see your a begginer, and that you did try. There are a few ways this could have been vastly improved.
1. Higher Framerate. It seemed like each character moved 10 feet a second. Crank up the Framerate to make sure it looks like they glide.
2. Customize the Sprites. For example, in the scene where the dragonfly blows up the pipe, I found the explosions to small, and took to long (look at number 1). If your were to spruce them up a bit it would be better. All you have to do to make this better is have things like little sparks fly out. Another scene with this was when the koopa got the star. That shine didn't look epic enough. One thing you did well here though, is the koopa's star form in which you cycled between the 4 shell colours of mario world.
3. MUSIC!!! Music would vastley improve this piece! Heck, any music you want! The first madness had the freakin' chicked dance!
I can definetly see more work from you in the future with this.