Humble? Look at the first two sentences after the introduction: "I am indeed the main individual behind the interaction design and implementation of the circle editor. I conceived, designed and implemented a compelling prototype for it almost single-handedly". And then, the first sentence of the following paragraph "Steven Levy's excellent Wired article got the story right - I wrote the circle editor and then recently widened my focus to the overall Google Plus user experience."
In my opinion, in order for me to believe Andy is actually humble, the last sentence, "Suffice it to say that Google Plus is the creation of large, talented team that I'm proud to be a part of", should have been the first one.
I think you are missing what he is actually doing - he states that the part he is wholly responsible for is just one tiny part of the whole, and that all the other credit given to whom is wrong. His first statement is meant to be a bit ironic.
In my opinion, in order for me to believe Andy is actually humble, the last sentence, "Suffice it to say that Google Plus is the creation of large, talented team that I'm proud to be a part of", should have been the first one.