Oars across the Atlantic wouldn’t be impossible, but certainly impractical due to the size of the boat, the number of calories burned and the amount of food they could carry.
Remember the Kon-Tiki? A balsa-wood raft? As the link below states, while Thor proved it could be done, it was an impractical way to colonize. Still, genetic indicates that, like the Vikings in North America, there was clearly contact between Polynesians and Native Americans who came over the Bering Strait over 11,000 years ago. Your comment about “if there’s a will, there’s a way” applies. It amazes me how much people could do when they weren’t busy watching TV or playing on the Internet. LOL
https://geneticliteracyproject.org/...-ancient-americans-really-settle-the-pacific/