The image on the right is in Solid Shading mode. It has nothing to do with rendering. Switch to the Rendered mode to see what the result will approximately be:
For Sun lamp you use in your scene the position doesn’t matter. Only its rotation influences the scene.
If you want to make your scene brighter, add more lights and/or increase the strength of light sources and/or increase the strenthg environment lighting and make its color brighter.
That’s object mode on the right. That color doesn’t mean anything in the final (F12) or preview render (SHIFT Z).
I rotated the sun lamp and it did become brighter.
Also, too much subdivision on the face pieces. Ideally you’ll never need a level 4 subdivision except in displacement modifier.