It seemed more to me that Humanity was the galaxy's master race and that everyone else was a little worried that we were in the process of renaming the galaxy The Human Way. Within 30 years of First Contact, Humanity is everywhere in the galaxy. We're already innovating on the dominant technology that seems to have remained more or less static in the hands of the other races; we're in the hunt (as the story starts) for SPECTRE membership and Council membership, although other sentient races aren't being considered despite being around for centuries. (Oh, and we actually had a SPECTRE recruit years before Shepard showed up, and he only failed because of subterfuge on the part of a sitting SPECTRE.)
We're described as "bullies" rushing to get what we want and shouldering aside anyone who gets in the way. Even without considering that our species produced Shepard, we were still moving ahead at a ridiculous pace. Maybe it's just time for us to go dominate another 250 billion star systems.
Hey can't help but be what we are, it's no surprise the aliens keep abducting people from our planet, it's cause they hate us cause they ain't us.
j/k.
With all the fictional stories about humanity being attacked by aliens repeatedly and them being superior in a killing sense to the point something like the creatures from Alien's can wipe out our best soldiers like nothing, it was nice to see a universe where humanity as a species is not only aggressive in terms of the galactic stage, but was shown to be the best suited all-around race over all, I thought that was awesome. I think it was harbingers analysis of the other races and humanity and why humanity was fit for the "Ascendance" that was Reaper molding that made the trilogy and battling against it so much more meaningful. I would not have cared nearly as much about relaying the other races and saving the Batarians knowing their history not only with humanity but with the Galactic Community as a whole. Just about every prominent race in the game kicked dirt in the face of humanity at some point or another, Salarians considered using humans as test subjects because of their wide range genetic diversity, (which makes it sound as if most other races were inferior), Turians were the first contact race humanity met and they were hostile towards us and still aren't exactly our besties. Batarians largely raided, human colonizes, and have more than a few times clashed with humanities Alliance forces either because of pirating or trading in humans. Also what's so wrong with humanity wanting more say in galactic affairs, as I recall a lot of the sitting council races were self lifted in that they discovered Mass Relays, the Citadel and the technology therein on their own, human is similar in that it wasn't "uplifted" like the Krogan, or Drell.
And of course we'd be called "bullies" though no history of hostile attacks on other races is documented, in fact its kind of like the exact opposite.