I know it seems like a very rudimentary question. You rate other people's games, they rate yours. But I've rated 25 other submissions and still only have 3 rates on my own. :( It's a bit disappointing because I worked very hard on my entry. 

Is it because I didn't get busy rating other submissions in the first 24 hours or so?...

Of course I'm not particularly invested in my ranking, but I would love to have more feedback on my game. I intend to put out a post-jam edition sometime in October, and I'd like to incorporate more community feedback into that version.

I do try to rate back the people that rated mine and also give feedback. I'd say an eye-catching thumbnail does the work of getting people into clicking but ultimately it's up to them if they want to rate or not. Some people abstain from voting games if the rating is going to be not-so good. It also could be that not that much people are actually playing the game enough to feel that they can give constructive criticism. Imo people play for a couple of minutes and in my experience they don't really read descriptions, so the game better be engaging in the first seconds or they leave.

(On another note, is karma not entirely related to ratings? I've rated & commented on 34 myself and i'm far from the top)

Perhaps this is an issue with Itch.io's UI/UX.