Some suggestions to make this great game even better:
1. Durability for tools. It would need some tweaking to make sure they don't die off too fast, but overall it would help the longevity of the game by adding another layer of resource management.
2. Weather! Rain can be a pain to program, but it would really add to the immersion to have cloudy days/nights and potential rainstorms. There could be wind or lightning effects that damage the raft, and as a plus, a surge of floating loot after storms pass to reward survival.
3. A shark lure. I've seen posts asking for better foundations as a way to deal with the shark attacks, and I thought this could be a cool alternative. It could use fish (mackerel or another kind of fish if any are added) and rope to craft, and ward off several shark attacks. It could even be repaired with more rope and fish over time, giving thatch a good use and making the fishing rod more viable. A drawback to the lure would be the inability to attack the shark, since it would just grab a fish and go, so if you want shark meat, you have to hunt it yourself.
4. Kindling for the Purifier and Cook station, made of either thatch, planks, or both, with a ratio that you get multiple bits of kindling from one crafting pieces (since it's pretty much shredded leaves or twigs). They can be loaded into the stations preemptively (say like ten uses' worth), and provide another use for thatch in the late game. It's also easy enough to make that it shouldn't hinder the early game
5. Building parts! Things like ladders (rope or wood) for a one tile way up a level and railings for a non wall alternative. Perhaps support beams that could extend out from pillars to allow more horizontal building without pillars everywhere. Thatch roofing would be cool, too, with both tile and edge pieces available.
6. More tree types than palm. Perhaps a fruit tree to keep in the style of trees being able to feed the player. Mangoes? They're very widespread, and they have pits, so reskinning palm seeds could work out there.
Okay, that's plenty of suggestions from me. I love what you guys have done so far, and I look forward to what you come up with next!