Not all those who wander are lost. ~ English novelist J.R.R. Tolkien
Humans evolved in Africa by 350–315 TYA. Like hominins before them, they had the traveling jones: spreading across the continent, and into Europe and Asia, in repeated waves. Ancient rivers and green corridors through what is now the Sahara Desert provided passage.
Some of the earliest forays were met by setbacks, as ice ages took their toll. Europe was especially inaccessible. When the weather was favorable, the diaspora was ongoing.
Many early technical innovations were made to facilitate long distance travel, including seafaring capability. These innovations diffused as cultures encountered one another.
Hominins reached California ~130 TYA, at the beginning of an interglacial period. They likely crossed the ocean to get there: an impressively courageous feat.
By 100 TYA, early explorers had expanded into western Asia. The temperate climate of southern Asia made for a relatively easy migration. Some headed east, all the way to the Pacific Ocean.
Moderns reached Australia 65 TYA. The only sign that there was land out of sight were the migratory birds in flight. It was enough.
Men were never ones to sit still. A wave of native Australians returned to the Asian mainland 20 TYA.
Humans first traversed the ice bridge of Beringia 26–20 TYA. People were in South America over 18 TYA.
Interbreeding was ongoing among peoples. The descent of humanity was a complex weave. There was no singular origin of the ‘species’.