User blog comment:Winstoninabox/DS2 Hollow Invasions/@comment-96.245.42.8-20140130140608/@comment-6003396-20140203063638

The primary role of Humanity, now replaced by the Human Effigy, is to restore your life bar after dieing repeatedly. Each time you die, your total HP will slowly decrease, along with your character progressively decaying physically – using Human Effigies reverses this process. Being Human/Hollow might have other roles that have yet to be revealed. The above is only what I am aware of.