Yes, it is probably the largest webpage on the internet, and surely the biggest one with a real reason for being so (it has to fit 7 billion people).
There is an extremely small amount of code behind the page.
Considering how big the page is, but also in comparison to a standard webpage on the web, the 7billionworld.com page is - in terms of code - very small indeed (only 13kB), thanks to the use of CSS background properties to reproduce all the "people" on the page.