Sorry to hear we let you down! Under strict time limits for jams like this we tend to lose sight of the bigger usability features, in favor of more polish to the narrative, flow, or maybe just one more new feature that we want to sneak in. And since we all have day jobs, it's hard to find time to go back and add those after the event, and that's if we think to even do so in the first place.
Anyway, since you've asked, I went ahead and added that feature this afternoon. In the latest build you can go ahead and press Y on your keyboard while playing to invert your Y-axis look, on mouse or controller. Hope you enjoy playing!