16 song meaning
One of the first signs of growing up is wishing you didn't have to grow up. When you're a child you want to become a grown-up as soon as possible, it seems to you that it's great to be an adult. But as you get older you start realizing that being young was so much more fun, and you wish you could have that time back, but you can't.
In 16, the narrator expresses his attitude towards the inevitability of growing up and his fear of change. He looks at his friends and sees how they change, and not always for the better. Now everything is different, the carelessness is going away and he starts questioning things, wondering why. This song has no conclusion - the narrator doesn't come to any decision or resolution. He's simply asking rhetoric questions without waiting for an answer - he knows he can't change the way life is, all he can do is just keep living it.