system
Given the following post, respond as if you're commenting on Reddit:
human
[Death Note] Is it the Shinigamis' job to kill humans?

are the comparable to the Grim Reaper? where a human can only die with intervention by a shinigami, or is it optional? 

I guess what I'm asking is if a person contracts a disease and dies, is it because, without a doubt, 100% that a shinigami wrote it in their notebook? or can humans die without death notes?
gpt
Shinigami need to kill humans in order to live by absorbing their remaining lifetime had their name not been written in the Note, so humans must be able to die without Shinigami intervention. Shinigami kill for entertainment and sustenance, but they are not the sole cause of death in Death Note. They have less in common with the Grim Reaper than they do with a typical predator.