system
Given the following post, respond as if you're commenting on Reddit:
human
[Destiny] What is going on?

Just started playing destiny 2. Have no idea what the plot points are.

Why can't I die? What is the light? What is my goal?
gpt
Broadstrokes here.  The traveler (big floating orb)  showed up one day.  Accelerated humanity into a golden age of colonization and prosperity.  Terraformed most of the solar system and generally was good.  The darkness showed up centuries later to kill the traveler.  Traveler tried to run away but an ai that controls nearly every weapon in the system forced it to stay.  Big ugly battle breaks out most of humanity is wiped out.  The traveler pretty much cripples itself to save what it could.  Guardians are chosen people and machines of the traveler given a sliver of it's power to protect everything that's left.  They're nearly immortal. If their ghost dies they can't be revived.  And super powered.  They defend the last city and a few other bastions against the darkness and other monsters.  Your goal as a Guardian is to beat back the darkness and save the system.  You fight the fallen who were previously aided by the traveler but abandoned.  The vex time traveling race of machines.  The cabal conquering space turtles of doom.  And the space wizard guys that are half dead and worship worms and the darkness itself.