How resilient is the human body?
The human body, on a scale of 1-10, 10 being most resilient, would be a 10.
The human body is wired for survival even if it is under great stress or injury. If there is danger, there is the fight or flight mechanism. If there is an injury, there is what we call negative homeostasis. Negative homeostasis can be seen for example when someone is bleeding due to injury.
Cardiac output is determined by Heart rate times the body's blood volume. If you are bleeding, the blood volume decreases which triggers the brain, particularly the vagus nerve to make the heart beat faster to compensate for the losing blood volume. Before a person dies from bleeding, his/her body would have had its heart pushed to the limit which triggers a cardiac arrest because of this mechanism.