I agree with you, but in Daiker's defense, the edges in the original image were already jagged.
Yes, I all I did was clear the backround. It was originally jagged. Also perhaps I should fill it with black?
No, don't just fill it with a solid color. At the very least, use GIMP's Blend Tool to fill it with a gradient.
When you want to try something more advanced, try learning how to use brushes downloadable from the Internet.
I used to like using brushes, but it's just the easy way out to make something look better. Now I try to avoid using them.