Neanderthals got to Mediterranean islands using what had to have been boats 200,000 years ago. Of course we know nothing about the boats. It must have been terrifying to be first. One thing we have learned about island populations is that a small population loses cultural knowledge over time. It is reported Tasmanians had lost the secret to making fire by the time Europeans got there, something I find hard to believe.

Anyway boats were re-invented many times in pre-history.