But for a single fragment of system the aim is-
Bacteria are single celled organism and is self-sufficient. so its primary aim is to save its own identity first rather than its species(reproduction)..
But our white blood cell which are also single celled organism, but is a fragment of bigger system(animal/plant). And so its primary aim is to save the identity of the system(animal/plant) it belongs to rather than saving its own life..
Though this answer is consistent with all System, but it seems something is lacking in that answer. How come a huge bunch of atoms and molecules knows that he has to preserve the identity??? How does the laws of physics is aggregated to frame such a rule of preserving the identity??? And also we,the humans, do more than just preserving his identity. Humans usually spend his most of the time to enlarge his identity,and not just preserving it.. Why humans do this?? Which extended law is governing it to do so. Sure its the evolution from atoms to humans,but everything is controlled by laws of physics only.. The more complex system means the more aggregation(by random number generation) of laws of physics.
With the answer, i’ve got a new and more confusing question or task to find how does the basic rules are aggregated to form a complex rule….