1. facebook did not "invent" anything, especially compared to Google, they copied text entry boxes and messaging, which anybody could easily duplicate from myspace and reworked the design. Google invented something.
Are we really going to describe these things as "innovations"?
You have to be intensely desperate to list these two trivialities as innovations.
I personally think that limiting the early user base to elite universities was the more important innovation for Facebook’s success. It allowed them to control their growth while creating an “aspirational” platform that could be scaled out later. I am surprised that more companies haven’t tried the same approach - it would be hard to do now, but the value in targeting this community is still there.