Some 120,000 years BP, a small group of H. erectus crossed the Bering land bridge to the Americas. This group would had died *here* without any interaction to H. sapiens, so they did have very little impact in how modern humans evolved and settled the Old World.
The group, however, survived and settled the Americas, evolving into what we will call H. americanus. The americanus settled both North and South America forming small familiar groups. Hunter-gatherers, they pressured the wild-life in the Americas provoking the earlier extinction of a couple of America's megafauna species; but also provoked the evolution of some megafauna species into animals more aware and fearful of human presence.
Probably between 40,000 and 25,000 BP, the first modern human beings arrived to the Americas via sea to South America, let's call them Murrayians. Modern human settlements begun displacing americanus, mainly out competed by the newcomers. Only in the most remote forests and mountains in South America did a few americanus varieties survive, until the next big migration.
Between 12 000 BP and 10 000 BP, a group of H. sapiens crossed the Bering land bridge into the Americas, let's call them Amurians. More aggressive predators than the H. americanus (or even the Murrayans), together with the climate changes at the end of the glacial era, the Amurians colonization of North America was followed by the virtual extinction of the North American americanus and several megafauna species.
Compared to OTL, however, at least two species survived: a small horse and an Appalachian camel. As happened before in South America, the americanus was displaced into isolated groups in the forests and the mountains.
By 500 BP, five varieties of former americanus were recorded: the Rocky Mountains man, the Tundra Man, the Central Andes Man, the Southern Andes Man, and the Amazon Man. Differences between them were big and no experiments were carried on to check if they were still the same species. Four of those varieties are presumptively extinct today, with the Central Andes man represented by 8 known individuals.
Murrayans were skillful seafarers but most of them lost their skills after generations in big continents such as Australia or South America; there is evidence, however, of a continuous trade between Africa and South America up until 2200 BP when the expansion of the Mediterraneans and their bigger ships begun cutting off most African ports.
The Appalachian camel, bigger than the Andean llama, was tamed ca. 6000 BP when Mesoamerican maise reached the Mississippi. These factors gave rise to a big culture in the Mississippi basin. Potato had been tamed from 8000 BP, but no big cultures were developed in South America before 5000 BP when maise began to be available in the Parana basin.
A series of diseases, plundering by Mediterranean pirates on the west African coasts, and the destruction of the last Murrayan communities by Amurians in the South American east shores stopped the more or less active exchange between Africa and South America ca 2200 BP. The contact between the Old and the New World was re-established in the North Atlantic when Laurentian sailors met Scandinavian ones in Iceland, 1050 BP.