I like the idea and have been looking for a game that woudl play like this. But I see some issues, and they are issues that should be be resolved before them work too much on NPC AI and skills. What kills early games is too many idea sn too much complexity that makes balancing things harder and they less more opeaques when played. "What am I doing wrong?" is not what they player should be saying, they should see "Oh I just need more or this types of sailor, or I need to build large cannon not lost of small cannon."
They have TOO many common sailor/npc types. The Scout, Fighter, Seadog, Seaweed, Shellback, Slimy Pollywogs are shoud all be compressed into three types. because are too too much to keep track of. Captains, Helmsman, Carpenter , Chef, or Cannon Expert do EXACTLY what their names imply. SeaDogs should just be your best fighters, sailors, and swimmers. ShellBacks shoudl be your good sailors and swimmers, but not as strong fighters. And Pollywogs your 'only okay' sailors and fighters, but they drown in water.
With that simplicity they developer and then just work on making a bigger maps with more stuff to do and more charcter to meet. Simplified mechanics to test yourself against more scenarios and situations.