Yea, if you submit it the way it is, I'm sure the judges will just say that it is just a rip of the original with different instruments, I've seen many decisions like that. The problem is, basically, all it is is a single percussion line with different instruments alternating playing the single main theme. You have to do a lot more stuff like playing around with the melody, harmony, just basically making it more musical.
Of course, it's a good start and the instruments don't sound bad or anything, just take that to the next level with the actual arrangement.
Also...I'm pretty sure it's not from Super Mario World.