Hasn't the idea been debunked that neanderthals were ape-like idiots incapable of cooperation or sophisticated tools?
Flint arrowheads versus microchip fabs; same species.
Perhaps there has been selection for sophisticated tool making abilities.
Neanderthals were baddass, they probably made better tools out of stone than homo sapiens sapiens typically did. But their minds were kind of... too narrowly focused. AFAIK, you could draw a plausible parallel between them and the dwarves of Tolkien fantasy.
The difference is that Neanderthals had hundreds of thousands of years to adapt to the environment of Ice Age Europe. They had even evolved actual physical adaptations to help them with the cold.
But the humans who moved into the Arctic only had a few thousand years at most to adapt, if that. Neanderthals certainly weren't dumb and primitive, but as you said they were narrowly focused. Modern humans were able to rapidly adapt their lifestyles and technology to allow them to thrive in extreme environments such as the Arctic.