Not really, the oldest Scandinavian kings that historians are pretty certain were real people were Harald Fairhair who was king of Norway around 900CE, Gorm the Old who was king of Denmark around 930CE, and Eric the Victorious who was king of Sweden around 970CE.
And the sources we have for the ancient kings were usually continental scholars, monks, bishops, or missionaries, who most probably had an agenda, and an antagonistic view of the pagans up north. And likewise, when the Scandinavians told their history to the weird people from the south, they probably embellished their stories.
...unlike for example Charles Martel and early French dynasties, who were 200 years earlier than the known Scandianavians.
Sorry to burst your bubble, but Scandinavia was a completely uncivilized backwater. :-)
? 'Pagan culture' is not some unified set of cultural norms. Rather, it's a broad category of possibly totally unrelated activities. Some of them codified via Rome (but those were adapted to Christianity) and then other, local ones.
The Christians in 300 CE were the most organized group on the continent, which was part of the reason the Emperor adopted Christianity.
An organized group of busy bodies might cause the decline of some thing (i.e. paganism) but certainly not the decline of the written word, education, governance etc. just the opposite.
One might argue that with the failure of Imperial Order, and the onset of tribal wars, it was the monks that carried most of the flame of civilization, which eventually led to the renewal of civil order and the reasonable ability to establish something approach civility.
Which is maybe close to the classical 'dark ages' narrative. Now of course maybe it was not as dark as we thought, but we certainly don't have a lot leftover from that time. Hence the historical narrative.
I also don't believe that Christianity had the power to destroy civilization. They were just the result of the decay of economic power of Rome, which lead the people to organize around something other than the traditional government structure. It also had to do with the idea that the old gods were failing to defend Romans, so why not joining this new cult that seems to protect the poor and dispossessed.
So at least on that end another reason for the break in history and lineage is that the people are completely different and in fact have no lineage back to Roman times.
Even though centuries later they converted to Christianity and started wondering why they don’t feel as Roman as they should.