I'll be honest - finding any sort of 'original' concept E.G. one not already associated with one of GW's 20 Primarchs, is going to be quite hard methinks; each one of them represents an emotion, a combat doctrine, and so on, and coming up with something unlike them might be somewhat of a challenge. Of course I'd not just copy & paste a Horus wannabe, but if I tried...say...an Ice Worlder who focused on sneak attacks and envelopment, it'd be like some sort of icy Alpharius. 

Yes, I'm probably thinking way too much into this, but that's how I see it!

Will it stop me creating my own superhuman superhuman? Of course not. I'm here to crush enemies and spread the Imperial Truth...as are we all. *Shifty eyes*