I liked the art style of the game. I thought it worked really well for the gameplay.
For gameplay, I felt like there was a story, but it didn't mesh well with the gameplay of eating the fish and avoiding the jellyfish. Maybe if you tied it in somehow, like make the player find so many fish before being rewarded with the next dialog or letter.
The story is an interesting subversion of the usual my parent's not my parent. I thought the reveal twisted it pretty dark, though, and the ending didn't leave enough breathing room for the player to process. This is probably because it's a jam game, but if the story were to be stretched out longer, the player would definitely need some time to anticipate, process, and decide whether they agree with the actions of Jo and the reaction of Tip.
My favorite part of the game would have to be jumping up out of the water. For some reason, I did that for quite a bit of time. Maybe you can "follow the fun" there and expand on that mechanic if you were to take it further.
Overall, I love to see a story-based game in a game jam! Most of the time you see a pretty standard prototype, light on art and story, focusing only on the core element. This game, however, has more story than most. That was pretty neat!