Being a Hero is just one of the decisions you can make on Origins. Being a hero consists of healing others, killing zombies, and killing Bandits.
How much Humanity Do you need to be a hero?Edit
Level 1 Hero = 2900 Humanity
Level 2 Hero = 6500 Humanity
Level 3 Hero = 15000 Humanity
Level 4 Hero = 49000 Humanity
Level 5 Hero = 2,000,000,000,321.0923 Humanity
How do I gain Humanity Quickly?Edit
Giving someone Painkillers - Gets you 20 Humanity (but gives you a head ache)
Giving a Blood Transfusion - Gets you 20 Humanity (but leaves you feeling empty inside)
Using Morphine on Another Player - Gets you 20 Humanity (but may cause their dependance to the medication)
Bandaging another Player - Gets you 20 Humanity (but also earns you a friend for life)
Killing 10+ Zombies within a minute or so - Gets you 300 Humanity.
Killing Bandits - Gets you 500 - 1500 Humanity per bandit (Depending on the level of the bandit)