In my opinion, if you've done work with a lot of different companies, that's actually great experience to have as a college student! Working is one of the best ways to get exposure to different sorts of problems and ways of approaching solutions.
Personally, the way I find problems to solve is by trying to do everyday sorts of things---be that building an app, game, a scientific simulation, a data analysis script or whatever---and then observing what's hard about it. Do this a couple times and you may start to see recurring problems. Usually my biggest problem is that I tend to undersell myself because these issues seem "obvious" to me after I've been in the trenches for a while. But sometimes the obvious problems are the most fundamental.
Anyway, if you have ideas of your own, I'd say just go for it. The instructions say they're "adjust[ing] for whatever life circumstances you were born into", and I think it's probably not unreasonable to expect them to adjust for e.g. age and stage of life as well. Compared to people in similar age categories I think you'll compare favorably in an application like this.
For anyone else who is interested, it might be fun to have an organized "Show HN" where we exchange and critique pitches.
Edit: Since this is getting some upvotes, here is what I propose: I'll post a "Show HN" here at around 10am PST on February 15th. People can reply to that with links to their pitches, and then everyone else can respond/critique in the replies. (This should leave enough time for people to edit their pitches based on the feedback they get.)