Humans are boring in the exact same sense that the Champion subclass of Fighter is boring. Which is to say, there's nothing that needs to be fixed; it's
supposed to be the simple choice.
As pointed out elsewhere humans are the default. When it was acceptable to couple racial penalties to bonuses this was tolerable.
Just because it's all now
phrased as bonuses doesn't change the fact that compared to the human baseline, most other races are "+1 to one ability score, -1 to four ability scores".
Now, the specific construction of the standard array reduces the impact of that. But in random-rolling it can have more of an impact, and in point buy you can create heavy-on-odds arrays like [15, 13, 13, 13, 11, 8], [15, 15, 11, 11, 11, 8], or [15, 15, 13, 11, 9, 8].