As far as i know, Humans was allways weakest Race in all fantasy i know ... maybe except Dragon Age, where city elves seem to be even weaker ...
Human power is not in stats, since individual human is in any matter worse than litteraly any other race, their strength is in numbers.
Not sure about other settings but Humans dominated D&D through 3.5e. Not sure about 4e. 5e is the edition where humans got the shaft.
Early editions, only humans had unlimited levels in any class. In 3e, they got a free feat and bonuses to skill points and no restrictions to multiclass.
5e humans are pretty weak. It’s like the developers wanted people to move away from humans. Very odd.
