My answer here is largely going to be
I do not know.
When we get right down to it: I am not a psychopomp. I do not see into the mind of the Norns and their designs, while I may occasionally talk with Hel I don’t spend a lot of time in her realm and don’t get a
back stage tour into the mechanics of what is going on.
So the long and short of it is my theory tends to be
I do not know, will find out soon enough, and so I don’t worry about it. I also believe that many people place such a huge emphasis on what happens in the after, they lose sight of what is happening around them and what is important now.
That said, there are a few touchpoints that I use when discussing this. I have seen enough to convince me that there are past lives, at least for some people in some fashion, and that there is some reason that most don’t generally have clear memory of what came before.
Beyond that, I don’t know about the mechanics. I know you can talk to manifestations of the dead, but I don’t know what their exact nature is. But as with many things here: All models are wrong, but some are useful.
So I will interact with the spirits of the dead, visit Hel’s realm, or assist souls in crossing if I am called to do it. I see what are supposed to be souls of the dead in Valhalla and Helheim, but ultimately I don’t know that such is what they are and it doesn’t bother me that they might be a manifestation of something different.