Mouse movements/clicking are pretty slow and bot-like. Besides that, seems like a solid script for your first attempt. I died after 20 minutes of running it (Wasn't babysitting, not sure what killed me), and it stood in Lumbridge castle doing nothing until I checked it. Maybe add a failsafe for death, or when no chickens can be found after X attempts?
Another suggestion, maybe add an option to loot/bury bones?