There were two main things I was thinking about when I started Dawn of Time: Dinosaurs and barbarians. I've loved Dinosaurs since I was a kid, right? But more recently I've been reading the Fafhrd and Grey Mouser stories, and now Conan the Barbarian. It's not so much the barbarians themselves as the storytelling that really caught my attention, because the feel of these old pulp stories and the way they're told is totally different from most fantasy I've read before.
But the reason I say this is because just as I started up Dawn of Time (or started thinking about it, anyway) a bunch of comics just popped up on the same sorts of topics! Dawn Best started up a comic based on the old Primal Rage games, so Dinosaurs and humans abound over there; Dave Reddick launched his Conan spoof Legend of Bill; and the other day somebody pointed me to Gastrophobia by David McGuire, a comic about an Amazon warrior (and her son), which we all know is just another form of cavebabe (the appeal is the same for me, anyway).
I just think it's interesting!