No lighting is working at all I have tried switching the layers and setting the sun brightness to 10000000000000000 but nothing seems to work, and everything stays dark.
There are two layers. The glass human is in a different layer.

The render with a bright sun:




blend file:
https://drive.google.com/file/d/1bFSneuIuCyh5BTJo0AOcp59ICcAd8jmz/view?usp=sharing
You set the "Clamp Direct and Clamp Indirect" to a very small number.



Here is a screenshot with,

Clamp Direct = 1, Clamp Indirect = 10, Sun lamp strength = 2.

The documentation for these settings is here https://docs.blender.org/manual/en/dev/render/cycles/settings/scene/render/integrator.html



Clamp direct will make all light values larger than the set value be ignored (or clamped), so if you set clamp at 0.03 for example, all light values will be considered up to 0.03, even if your light is brighter than brightest star in the universe.