I see no problem with this. You can find screenshots of all the hats herescreenshots of all the hats here, including a link to the sprite sheet (which also includes some "troll hats" - red herring hats that weren't actually earnable).
If you use any of these hats in your game jam logo, we just ask that you credit the designer who created this year's batch of hats, Elias Stein, in your blog or meta post (or wherever else you are announcing this).