This is super cool! I do have a few suggestions:
1: Add an option to leave when you get the boat so that you can keep exploring.
2: Add bridges to travel easier
3: Add bows and arrows
4: Skeletons with bows that sometimes drop
5: Types of potions
6: Armor (stone, iron, gem, etc)
7: Large inventory limit
8: Section in your inventory just for tools
9: Make some way to throw items to get rid of them (like your old wooden tools)
10: Make items last for longer
11: I don't know if this is possible, but could you add hotkeys for items? (Z + up, Z + right, etc)
12: Different modes (creative, normal, respawning)
13: Different table/bench to make gem tools/armor (like a forge or something)
14: More buried treasure and tailsmans
15: Different types of walls and doors to make a base (wooden wall, wooden door, stone wall, stone door, iron wall, iron door, etc)
Ok, it might have been more than a few suggestions, but I think that these changes would make the game more fun, while not exactly copying Minecraft.