Nnnot really I think? Honestly you're sort of approaching this from the wrong angle.
The Primarchs are the product of not only a fully intact Emperor's labors ("I don't see why women always complain about giving birth" says the Golden Asshole as he plugs another tube into the incubation chamber) but also a fully intact
Imperium. This was before the Horusy, before known space was rent in half, before the Imperium turned bloated and cancerous with worlds beyond its ability to effectively manage and before the brutality set in. There were resources, technology, knowledge that went into their creation that's since been expended, corrupted, or just lost; to say nothing of their maker. The Primarchs, from their very inception, were deliberately
designed. There was a logic at work, a genius and an intent. They were as far from a collection of semi-randomized traits as you can get and, sure, they were then basically dumped in the wild and raised by wolves ('eyo Russ) but that doesn't change the fact that they were part of a plan from the very beginning. Insofar as the Emperor has biological offspring they, truly, are his sons.
And they are complete bullshit.
Us?
We're a shard of the God Emperor's self that he calved off and I really really doubt that performing desperate psychic surgery on your soulscape while you're a very depressed cyber-corpse is, uh, as clean or as methodical as an operation under laboratory conditions. We're also
us which is to say a semi-ordinary dude who climbed to a position of power will all the varied missteps and setbacks and ill-considered choices you get along the way. We're a person who's already had a long, rich life even before we turned back the clock on our bodies and even
before we got the Exaltation. We're not planned. Honestly we're a bit of a mess considering how everything turned out.
We're deeply flawed, albeit in a normal, human way rather than the insane galactic-scale way the Primarchs are.
What I'm trying to say is that unless we monofocus in on fighting and direct-combat stuff then pretty much any still-living/returning Primarch could still crumple us into a very bloody basketball and slam us through a hoop so hard that the backboard shatters. And that's
fine. We're starting from square one with different, weirder tools, and absent many of the resources and opportunities they had. That's what it means to get this kind of power in a fallen age and that's
fine.
Honestly the really interesting thing is that...I was sorta joking earlier but I did mean it, in a sense we
are their foster brother. For all that Daddy Emps gave us a golden haymaker and went "WELCOME TO THE FAMILY SON" he did recognize us, anoint us as one of his heirs. Even if we're inferior in many ways to a Primarch we're still their
kin. And they're going to have a variety of reactions to that I think, them and their descendant Space Marines. Ranging from "Classic dad..." to "OH SHIT NEW BABY BROTHER WHADDUP" to "how fucking dare you i will chaos dunk you so hard the crust shatters".
Which I'm legitimately looking forward to
.
