I'd restart that game tbh.
Random thoughts and reasonings:
1) The island is not very rich - you got only gold, pearls, crabs and silver and all except the crabs are 1 of.
2) No neighbours means no trades for luxes.
3) Not being able to get happiness will hinder growth
4) In order to meet someone you have to go to optics fast, and thats going to delay growth as well. You can try with the trireme, donno if u can reach someone.
5) You don't even have a CS on the island, so you cannot even build a caravan. Food ships are good, but u will need happiness for that growth ... Not to mention that you are going to get also no quests.
6) As you do not have trade partners, sooner or later you are going to start losing gold as well.
So as a summary, you have a big island for yourself, but u cannot expand that much, and at the same time you cannot really grow very tall as well, unless you get lucky and the AIs find you really soon. You are also not in a good position to find em yourself fast as well, as if you want to do that, you need to research rather useless starting techs like sailing&optics, and that might even not be enough, as its possible that you need Astronomy to find another land mass ...
So while you try to handle all these problems, some AIs will get huge tech lead over you, that you are not going to be able to overcome .
I can't say that this game is unwinnable, but its definitely not the game I want to play.