You definitely did a great job on clarity--I read this and can immediately envision what this game would play like. It's long, but not excessively long because the information was clearly presented and useful. This is clearly a project you are passionate about and that shows through, especially in the characters. I like Blue Streaks and the rollerblade mechanic specifically. It definitely evokes the feeling of an old-school game from the early 2000s, so spot-on there.
This game doesn't really have anything to do with the theme of the jam since it's not a new genre. But of course it's perfectly fine to make a GDD not for the theme--the theme is only one category, anyway.