Through his poem he makes a clear message that is easy to understand: where we come from. It's not about our roots and heritage, it's more about what we are actually made of. The carbon we are made of, the oxygen we breathe, the sodium chloride we consume amongst the sulphides, glucose and ascorbic acid. All of these are the building blocks of our everyday life.
Where did this all come from? How did such a combination of elements create who we are? Are elements intelligent or did it just happen? Obviously elements do not feel anything but, assuming current molecular designs are correct, what creates the affinity between molecules? There's definitely something there, hence why quantum physics exists, but it's amazing to think about when it comes down to the atoms and what they are made of.
Maurice McNamara is right, we are made of dying stars, space debris and stellar remnants from light years away. The buildings we build, the mobile phones we use, the clothes we wear, they all came from a dying star and it really puts everyday life into a spectacular (perhaps an astronomical?) perspective.