Open world is a bit negating because then it becomes environment based, and the odds of an average person outsmarting a gorilla are much higher than a person defeating one in combat. I could probably beat a gorilla in the open world if I could lure it under a ledge then drop a huge rock on it.
But in a gladiator environment, I'd say a peak human would need minimal protection. In the Roman Colosseum battles, humans were put in there with tigers and bears and all kinds of exotic animals and would on occasion prevail. Though contrary to popular belief, gladiators weren't ripped with a six pack, huge muscles and armor. They wore minimal armor, covering parts of their arms and legs, and sometimes a helmet, but it was considered cowardly to protect the vital organs, almost like cheating but not really. And because of this, gladiators were often burly, eating high carb diets and put on fat around their stomach area, which was often exposed.
I bring all this up because I think the standards of history show that a peak human could win this fight, but they'd need a bit of protection and something sharp. Then it becomes a bit of a toss up.
