I'm not really sure what the song means much. But I get a sense of a much softer side of Fergie. I liked the song because it was very soothing, and the lyrics was quite touching. Yeah, innocence definetely can be used to describe the song. Tho, I noticed that she has a "rounded" sorta voice when she sings the high notes..
p/s Fergie's voice sounds different in lots of songs- Glamorous, Fergalicious and this one. Tho in a good way.