This game is already great for a alpha with allot of potential.
Ideas: Enemy NPCs that will drift to your raft time to time, rare loot like a better named hook than can reach farther and do damage, a pirate ship that attacks you and if you defeat the pirates and captain then you get allot of rare loot that's drops when the ship sinks after the battle, neutral NPCs on small rafts with possible loot, islands that you can visit by crafting a small boat and finding a map to it, weather system with lightning that can hit the raft and to put it out you use a can of water, sleeping system, nightmare mode where it's always nighttime and sharks attack more frequently, more shark types, being able to go underwater for a short amount of time and finding occasional Chests, tool durability, reinforcements for foundation, a writable journal and a story of how you ended up on the raft with mysterious flashbacks.
I understand that it is only a small group working on the raft, but these are just ideas for possible features for the future. Rome wasent built in a day and neither will raft