According to the geological record, the last time there was no ice at the North Pole was more than three hundred thousand years ago.
Since long before that time humans or hominids had roamed the planet, having either originated in Africa or having evolved in various places simultaneously, since they also appeared in the orient three million years ago.
There are few niches that will not become occupied by life within a few thousand years, by humans too, so even the colder places of the earth were soon taken up(1). Therefore you can safely say that the ice was soon occupied, as it still is today, by bears, with those whose hair mutated white and skin black surviving there better, and by the humans. Today we know these people as the Esquimos, and they know themselves as the Inuit. Good luck to them. They need it, as do we all, as you will see.
If you look at the Inuit, you will see that they are of Oriental origin. Ingenious folk, curious too. So, in the same way that they explored and used the possibilities of the ice, they also then explored the land to the south. If they came south there they were in what we now call 'Greenland', here 'Scandanavia'. If they ventured south further along they were in 'Russia', there 'Siberia', there 'Canada'. Where there were previously no other humans they persisted without intermixture and filtered on south.
If they explored only twenty miles per generation in 'the Americas', within a mere ten thousand years or so they had already reached the tip of 'Patagonia'. Darien might have delayed us modern softies for awhile, but nothing would have stopped a species hardened to Arctic survival and competition with the savagery of animals in the untamed wilds of then. Besides, fluctuating sea-levels would have made shoreline travel comparatively easy.
Presumably there were later arrivals to 'the Americas' as other orientals passed from 'Siberia' to 'Alaska' when subsequent ice-ages lowered the sea level and bridged the gap, but their survival suggests the people generally ironed out differences among them and generally lived harmoniously as a race. They developed a kind of society somewhat different from ours, complete with saunas or 'sweat-lodge' type culture and civilisation sixty thousand years ago, and regular pow-wows or meetings of tribal elders, as in the recent Iroquois nation, where they buried any hatchets and smoked the peace-pipe.
They even developed sophisticated societies, complete with amazing ceremonial cities as in Central 'America', with massive stone-work that is so perfect that we cannot understand even today how they could have managed it, and their understanding of their natural world and of astronomy was remarkable.
More recently they sometimes used 'wampum' or cowrie-shells to facilitate exchange. But in the absence of greedy ambition and deception and without the invention and imposition of 'laws' of 'ownership' and so without the avarice of those whose business is always to start wars between other parties, they survived well enough and in harmony with nature.
Various other very recent arrivals, such as the Vikings and Irish and even the wily Phoenicians, who presumably couldn't find any handy 'St. Michael's Mount / Mont San Michel' from which strategically to trade, came and went without causing more than a ripple.