I like this, it works very well as a makeshift home thrown together in a hurry, which fits quite nicely with the backstory you provided. I'm not going to complain that it looks too random with all that stuff piled on there, because its clear that its meant to be. However, I do think it could stand to be a bit more realistic. Like others have said, some water and perhaps some ripple effects with clear plates would go nicely at the bottom. It's a shame you don't have a lot of blue, a 12 x 12 base with some other rock formations, waves and other details would do wonders for this MOC. I also agree that the rock formation looks quite unrealistic. I know I wouldn't want to make my ramshackle, probably pretty weak house on such a thin rock, with rough seas and possibly sharks below!

Also, a ladder going up from the main room up to the crow's nest would look pretty good, if you can fit it in.
But the biggest thing that I'm not crazy about is the mixing of Pirates, Steampunk, and even a little Castle. Taking away that purple shield, along with those Medieval-looking axes, along with that Steampunk-like wooden propeller up top, would make your MOC have a clearer definition, and really help with the atmosphere of the scene. To me, the mentality should be: "I'm stranded, I'll use whatever I could take off the ship to survive." Right now, it seems like "I'm stranded, oh look, a Knight's shield and some battle axes, along with a propeller that are all inexplicably here."
I'm not trying to be too hard on you, I really like this MOC, its just that I feel you added a few things that don't really make sense that take you out of the experience you were trying to convey. I like all the little quirky details you've got, especially the water tap and the redcoat hat on a pike.