It's mixing...

Lacks seriously, you should've done a MUCH better job, and it's you who must mix it well, and not us who should put their speakers' volume down.
It sounds as if you recorded it with a laptop microphone...
So either use a mixing program to try and make it sound better, or buy a better mic.

One way or the other, it needs improvement, the melody is not bad, doesn't really need any improvement.