"Every single thing humanity has ever created in the past 7,000 years" does not mean that all 7 billion people in the current day were working together to solve a single, common issue. At many points the groups were significantly smaller, and thus stuff got done, like basically every single technological advance we've ever made.
But take an issue like what humanity needs to survive, put them all in a room, and ask everyone to come to a consensus on what should be done, and what you get is not agreement but fist-fights and accusations and some smartass in the corner saying "Food, water, and shelter" than any actual agreement taking place. I dare anyone reading this to disagree - this is pretty much how it'd play out if you put everyone from Fidel Castro to that random creepy Internet stalker to end up making a decision.
I guess a better way to phrase it instead of intelligence is problem-solving ability.
So... nah, I think my equation checks out, sorry.
EDIT: 100th post, and it couldn't be more of a downer. Sorry guys! Hope you don't... lose faith.