In the original 'Dark Energy' storyline, Humans WERE special. From memory, the ultimate choice was to either sacrifice humanity to save the rest of the galaxy, or save humanity and everyone takes their chances.
The 'Dark Energy' plot was ditched towards the end of the development of ME2. It was so late in the day that there are still a few references throughout the game. I think I read a while ago that the Human Reaper came about because the Reapers discovered that humans were special. Note, in this plot the Reapers were actually misunderstood good guys trying to prevent dark energy from destroying everything.