You do see a tree via sunlight reflected off it. Most (but not all) of the information in what is in your mind's eye comes from the tree and only a little bit comes from sunlight. Alternatively, you can think of photons as a way to deliver information about the tree to your brain.
Light is necessary for you to see the tree but is not sufficient.
An insight I had a while ago:
When I'm out in the daylight, and I see a tree, what I actually see is not the tree itself. What I see is the sun reflected off the tree. Likewise with rocks, grass and birds: it's always the sun I'm seeing reflected off them. This is possible because the sun emits all visible colors (or rather, our eyes evolved to perceive almost all EM frequencies that almost all solid matter deflects). I'm not seeing the things. I'm seeing the light. We live surrounded by the sun.
Is this too obvious? Inconsequential? Redundant?