Explain how Jim realizes he made a mistake in coming to the island. chapter 14

I think it is because he really doesn't know how he will get back to the boat.

anything else iv had trouble finding an answer for this question and need more detail.

He realizes that he's made a mistake because there's no way to get back to the boat without everyone knowing he's aware of Alan and Jim's deaths. If he goes back they'll kill him.

"There was nothing left for me but death by starvation or death by the hands of the mutineers."