I'm pretty happy with my first submission. There's lots of work left to do if the next person wishes, and a pretty strong thesis of what I think the game is about.
I was lucky that I came upon an idea that I was genuinely excited for early on, and I actually wrestled a little bit with the idea of submitting it to this particular jam. What if other people don't think it's a good idea and decide to do something completely different? What if it ends up looking like something I wouldn't want to play? But I think I'd rather submit something I'm genuinely excited for than feel like I have no skin in the game. Genuinely excited to see what it looks like at the end of all this.
I think it's probably best to start with something solid for this first stage rather than some loose fitting parts. Makes it easier to edit and change things in the later rounds. And that idea doesn't necessarily have to be the parts for an entire game! Maybe it's just a setting or a character class or a way of generating random factions. Hope that helps!