I think the problem mainly comes from the fact that a lot of people here are new to this kind of jam on itch.io. Naturally, newcomers tend to be polite and supportive rather than critical, especially in their first event.
There are also different ways people approach jam games, some just play for fun, others to analyze design, and some to check out what other devs made. Depending on which group you fall into, you’ll naturally give a different kind of feedback.
So yeah, constructive critique might be rare this time, but that’s just part of the community finding its rhythm. Once there’s more “culture” around proper feedback, I think we’ll see it grow.
My teammate and I have been playing some of the jam games and had a blast, but to give proper feedback we’ll need to replay a few. It’s never too late to learn from each other.