The answer about the Human race being as it is because they want to provide an "easy" race is a bit of a bummer.
It's the same mistake as in previous editions thinking that the Fighter should be the "easy class". This was bummer because players should not be forced to think "I am a beginner, I should play a Fighter" or "I am an expert, I should not play a Fighter". People should play a Fighter if they want to play a Fighter, obviously! Then the best RPG will let them choose between an easy Fighter and a complex Fighter. It's ok if some classes like Mage are impossible to make simpler than a certain basis, it's not-ok if the designers start with the assumption that some classes should be simple and others should be complex.
So how about races then? Well it's less of a bummer, but still a bummer. It's ok to think that trying to roleplay an Elf who easily lives hundreds of years or a Dwarf who lived underground until yesterday is going to be more difficult than roleplaying a human. It's not-ok to make a race purposefully low-complexity, when players normally choose race for roleplay/concept reason (ok, many choose it for exploiting mechanical benefits and min-maxing, but it's not related to complexity).
So how about this... How about, instead of having a "simple" race which forces every Human character to be simple, instead having a Human race that is just as complex as the others, but then having an option for everyone no matter the race, to have +1 to all stats instead of all the racial benefits package?
Beginners could play a human, dwarf, elf, halfling or whatever just because of the image/concept, and instead of dealing with all those little bonuses, they just get to increase all scores by +1. This way, there is a simple, easy, low-complexity option for race, without forcing the character concept to be "human", and without forcing non-beginners who want to play a human PC to get the easy package.