Here is the final word by Gainax themselves:>"We wanted to show human aging in Gurren Lagann. We will get old. We will get wrinkles. We will, sooner or later, eventually die. But it's not a bad thing. It is human, and it is happiness.">"When you are young, you tend to say things like 'Who do you think I am?' but when you get older, you find it who you are no longer matters."
The meaning of Simon's "I'm nobody..." line:>"Until he asks that, he wonders who he is… he starts to say who he is but stops. But in that scene, the boy doesn't care who he is. There is meaning that he is talking with a boy. Gurren is Simon's story. And it continues with the boy. So the boy represents the next generation, and the next generation doesn't care who you are."
And their final line for the event:>"If you are young in your twenties, please watch your Gurren Lagann DVDs again in twenty years. You might see something you didn't see when you were in your twenties."http://anime.miao.us/archives/2008/05/26/1416/