This. Humans hunted almost all big, meaty, slow-moving animals to extinction. Starting with the woolly mammoth. Seriously, a TWO TON wombat (https://upload.wikimedia.org/wikipedia/commons/1/18/Vombatus_ursinus_-Maria_Island_National_Park.jpg)? Something like _4000_ person-days worth of food (not to mention pelts, bones, etc.) with no natural defenses? Delicious, easy kill. All were slain.
Plus they probably rotted up long before they could be fully eaten, and then you had to get another.