For almost everything that's ever born, the world is a shit place. Animals muller each other all over the place, fish eaten by bigger fish eaten by bigger fish. Turkeys wander round waiting for Bernard Matthews to wring their necks. Even if you're born human, you'll probably have a bit of a rubbish time of it. Be a woman in the wrong place, or black in the wrong place or just alive in the wrong place and you'll have a piss-poor time of trying to get anywhere.
I have none of those things, but I still have depression.
It's a weird thing: I have a roof over my head, I'm not even close to struggling for food, water ...