Your use of color really stands out, even among a very colorful selection of semi-finalists. I feel the anatomy is a little stiff and, as pointed out, the thick waist throws the proportions off a bit but I think the excellent sense of movement and general flow to the piece overrides a lot of the anatomy; it just feels right to me.
I like your fanart but I do not like because it looks somewhat blurry sight, the colors are stunning but I do not like your legs because they are also compared with some fat waist. but I liked the message and inspired me with the image.
Don't think luck had anything to do with it. They were looking for originality in representing their characters. Your artistic style is good, out of hundreds maybe thousands you're in the top 25, if you win thats just an added bonus to that compliment.