One can also look at it from this perspective; Earth is alive cuz one of the definitions of life is in actual existence or use. It can also be considered as growing and living cuz it undisputedly constantly changes, therefore it must be alive. If our planet was not alive, it would just be a plain rock that was never different from the way in which it began.
How the hell could we've be born from, and be sustained by it if it was just a floating rock in space?
Look at it this way; Movement of Earth is repetative, it creates repetitive changes in it's atmosphere (for example changes in weather), that weather generates electricity (lightning), which holds the power to change the molecular structure of most substances it comes into contact with. Lightning creates and links chemicals, and can break them apart. We are made of many of these same chemicals. Believe it or not, our bodies do practically the same thing in order to support our internal metabolic processes.