Cool game,
Here are some features I would love:
Progression is way too fast in the end imo, running arount the continent takes way too long. Fast Travel on your continent
Different Themes of Pirates (Gunslingers, Ghost Pirates, Admirals, whatever) Each island has different attributes and gives your island different benefits so that every run is different.
Once you have collided with maybe ~10 islands on big "continent fight", maybe those occure randomly?
Ressource systems, trees that collect you money, workers,... creating different porpuses for areas on your continent
Different weapons for your character (guns, bombs...)
Traps for when you collide with islands
This game has so much potential for a unique basebuildung, towerdefense type game.
Please develop it further I saw your Youtube Video randomly with 700 views.
You will go viral.