Here's why:

* Photosynthesis: Oxygen on Earth is produced through photosynthesis. This process is carried out by plants, algae, and some bacteria. They use sunlight, carbon dioxide, and water to create their own food and release oxygen as a byproduct.

* The Sun's Role: The sun provides the energy needed for photosynthesis to happen. Without sunlight, plants wouldn't be able to produce oxygen. However, the sun itself doesn't directly create oxygen.

* The Sun's Composition: The sun is primarily composed of hydrogen and helium, not oxygen.

So, while the sun is essential for life on Earth, it doesn't directly provide us with oxygen. That crucial element is produced by living organisms on our planet.