The first modern humans originated in the northern part of what we know as Ethiopia around 200,000 years ago. Slow migration outward through Asia and Europe followed, and short island hopping through Indonesia and Australia. Around 14-17,000 years ago some Asian groups migrated to the Americas via the land bridge that existed at the time in what is now the Bering Strait of Alaska.
The first hominid came from Africa and back then the earth was together so when we evolve enough to have the brain mass to explore and for some reason unknown the earth became how it is today,simply and no Magic from a divine source needed
Around 1968, I read a book that began like this: "Not in innocence, and not in Asia was humankind born."
The book was AFRICAN GENESIS by Robert Ardrey, a fascinating account of our probable evolutionary origins. Several people responding to your question mention Africa as our motherland...and it is certainly an hypothesis worth considering.
Well, according to genetic markers, so far, supposedly humans started somewhere around Ethiopia, and spread out in all directions from there. Here's a map of the migration paths as shown by genetic markers, so far: https://genographic.nationalgeographic.com/human-journey/ . As to how they got to different continents, there's distinct evidence that they used a combination of methods, when migrating in groups, over time. They simply walked at first, later using animals to help haul their sled-like contraptions to transport items, eventually building heavy rafts to ride over water, sometimes over long distances whether by intent or accident.