Oxygen must be the most valuable element in the Universe. Right?
Ah. It is interesting to change perspectives. What if oxygen was a poisonous waste product? What if we evolved as opportunists who could use this waste product, this toxic gas in order to live?
Early cellular life on this planet were anaerobes. Oxygen was essentially nonexistent in their primeval atmosphere. Procaryocytes as these early cyanobacteria were called grabbed COs from the atmosphere and in a miraculous alchemy known as photosynthesis created themselves. In the process they released a toxic gas known as oxygen.
They were so successful as living beings that they nearly created their own demise. In what is known as the "oxygen catastrophe" 2.4 billion years ago, nearly all early anaerobic bacteria were extinguished by an excess of this toxic gas.
What evolved were known as eukaryocytic cells who were advanced enough to have nuclei and cytoplasm. They "knew" how to take advantage of this toxic gas and through a biochemical reaction known as respiration derive energy and life from it.
We are their descendants. Go figure