It doesn't take a genocide or a dramatic event to cause an extinction. We didn't have to hunt them to extinction, and a climate change didn't necessarily have to happen. It all comes down to energy in and energy out. If your net energy gain is less than species around you, then you will go gradually go behind.
Since every habitat has a certain carrying capacity, every step you go behind, another species will fill, and you will not be able to regain unless you improve your net energy gain. If you allow your species to go far enough behind, your gene pool becomes diluted, and once that happens your population is no longer viable and its just a matter of time. Extinction is insidious.
Even small things can make a big difference. Small calorie savings due to simple adaptations and characteristics add up, and give you that edge when it comes to reproduction.
On the philosophical part of it, I've never understood the resistance to evolution based. I know there is no religion talk here, so I'll be careful what I say, but it seemed to me that if there was a God, then evolution seems like it would be the kind way it would make its influence felt. But your minds are your own and your all entitled to your thoughts on the matter.