Pegged mortise and tenion caulked with bitumen from surface oil/tar.

https://en.m.wikipedia.org/wiki/Phoenician_joint used well into the iron age

Earlier were held together by rope like the https://en.m.wikipedia.org/wiki/Sewn_boat or the https://en.m.wikipedia.org/wiki/Lashed-lug_boat and caulked with vegetation. They were essentially “let’s take a raft and engineer it into a boat.”

Key point for both is you usually needed bronze tools to work wood like this. You could plane with stone axes easily enough to make a canoe but you couldn’t really make a mortise and tenion and sewing a boat together was damn hard with stone and bone tools(though there were stone bow drills with flint bits and some pretty damn impressive users, it’s how they made strung beads for early trade in the neolithic and late mesolithic).