Congratulations on getting a working prototype and entering a game-jam! :D It's a very good start and I'm sure you'll do a lot of amazing things. :)
I like these sort of games a lot, and I played this one for a while. You have a good idea here and there's a lot of potential additions that could make this game a really cozy trading-game!
I second what has already been said previously as the first thing that really confused me was the inability to know what was actually carried on the ship.
A minor issue I had was the transparency of the ui-panels, it occasionally got very hard to read.
And also, a tip for you on this game and something to bring with you to future jams and projects: audio! I know few things that can elevate the feeling of a game more drastically than sound vs no sound. Just a little feedback on button clicks or ambience would add enormous value!
I hope you'll push an update post jam. I will gladly get back to try it again! :D