(Carl's note: the other product is glucose. It is no less important than oxygen.  Both are useless without the other.)

Ponder exercise... (which came first, chicken or egg?)
When did the chloriphyl plants show up?
Where did the Carbon dioxide come from?
Where did the water get the oxygen to become H2O?
     The photosynthesis factory needs those "raw resources" to produce it's final product! 

It all was created instantly... but that word implies time-space, but that did not exist yet.  There is no "measuring- stick" of time until after the "moment of creation". Not all galaxies and universes have the same time base. Just how 'long' is an 'instant'?

Until we can disconnect our mind, emotions and will from "the clock", we can't "get it!"

Glucose is the Sun's energy stored in chemical form. Plants and animals can not "divide cells to grow" without energy.