I don't want to pile on, but you're failing to see the implicit cultural bias in your argument. Primarily, that calendar was created and implemented by the Church, at a time when that Church dominated political and cultural life in the Western world. Of course they decided to divide the calendar there, they accepted Christianity as a first principle.

>How many of those tales give you a single point of failure, that if you can explain away one point then internally the whole belief system collapses?

All of them, if you don't believe in the existence of the supernatural. But this argument, in itself, reveals another fallacy, as it assumes the narrative consistency or cultural relevance of a religion has any bearing on its actual truth. Reality doesn't have to be logically consistent nor does it have to follow a narrative path - one only has to look at scientific progress over the last century to see that. And the argument that Christianity must be true because so many people believe in it is undermined by the fact that more people have consistently believed otherwise over time.

>Seems to me there might be more to the story than just a random dart throw at a wall of choices.

Thing is, that's what they all say.