The increased accessibility of SM1 most definitely helped. To be very honest, the thing which got me into 40k was the excellent Dawn of War series. Not only was it one of the first fully 3D RTS games, but every one up to and including the two Dawn of War II titles are absolutely brilliant strategy games (with II being closer to Kill Team with reinforcements, granted).
Heck, I still play Dark Crusade regularly, one of the tightest and most enjoyable RTS campaign modes I’ve played to date!
I mean… speaking concretely, sure, they’re biologically human, but… when delving into the abstracts, this is at least highly debatable…