Native Americans didn’t swim here.
They walked over the Eurasian-North American land bridge.
When you read Geology you discover this planets climate has been all over the place prior to people!
Reunite Pangea!
There have also been suggestions that during ice ages the ice cap of permanently frozen sea ice might have dipped far enough south for ancient humans to have walked across the Atlantic to America. And some of the earlier tools found in US resemble Western European tools from the same timescale.
There have also been suggestions that during ice ages the ice cap of permanently frozen sea ice might have dipped far enough south for ancient humans to have walked across the Atlantic to America. And some of the earlier tools found in US resemble Western European tools from the same timescale.
In that case I guess the native Americans aren’t so native to America.