For an animal a bit closer to a Human, and one of our nearest cousins, a Silverback gorilla is around 5-9 times stronger than a Human, and can lift 4,000 lb (1,810 kg) on a bench press, while a well-trained man can only lift up to 885 lb (401.5 kg).
Apes have a Strength of 16 (size Medium) and Giant Apes 23 (size Huge) so you'd likely have a Silverback Gorilla somewhere in the middle of those two game stats, with 'Apes' likely representing something like an Adult Chimpanzee (also a crazy strong animal).