Just a bit of a theme reaffirmation for the last Arc it seems?
Cuz yeah, Guts is a threshold human, more fate-wise than being another species or something. This was always a thing, with him seeing supernaturals and all that.
I don't see none of this taking away from Guts himself or his bonds, his efforts, his story. Mostly seems like a compartimentalizing of it.
Just the way griffith was born in filth but wanted to cross the threshold to ascend (even if his dream was kind of simple, and God Hand sorta amped it to eleven and he rolled with it). While guts never wished to cross, he was aimless, until he met his comrades.
And I'm not sure, but isn't every soul from the Spiritual Realm? And then is born in the Material Realm through pregnancy? Don't know if this has been spoken of.
But it was a cool scene with Guts being shocked back to life, and taking his "first breath" like a baby.