Well Puke I actually like the Warhammer 40k universe fiction wise because it takes humanity to a point where we would probobly not recognize ourselves anymore if we saw them and we could not imagine that far in the future much less how technology would interact with us.
And a funny thing about that is if the Emperor had never been wounded humanity would probobly still be advancing and "enlightened" in the modern sense of the word where they see technology as just that technology and not as some mystic power of the gods. Also we can be pretty sure that the Empire would be ever expanding and not sitting stagnant like it is in their present.
There are rumors even that Games Workshop will eventually "kill" the Emperor and have him reborn into a "good" version of the Chaos gods and we'll see brand new things coming for the Imperium, I hope so personally because I like my IG forces and I'd love to get to add cool new tech
But anyway I've always been amazed at how in most sci-fi humans are just like "meh aliens" or "meh evil insectoids" and pretty much just pick up a gun or build a warship and march out to fight them like it was other humans and no big deal. And the huamn race overall doesn't change much and the government is usually still a "good guy" like the Federation from star trek.
That's in a lot of ways why I chose to write the Icaran story, where Humans don't just go "meh aliens" they are terrified to the point where they make it almost religious dogma that aliens are "unpure" and reduce them to the level of "animals" almost and declare war on them wholesale for the simple purpose of making sure they are never a threat to the human race. I wonder which way humans will really go when we actually step out there and find someone or something else.