I can never know the correct and full answer but this is as far I got till today:
Humans need:
1) to feel good in life, where a great part of that depends on our own understanding of what is right and what is wrong
2) to learn and to build their character, this includes the need for exploration of all that is unknown to them
3) to help others in achieving the goals 1) and 2) and to be helped by others in doing the same
Example: I like acting. Why? I feel good while acting. It helps me understand some things and situations in life, ideas and philosophies. It helps me socialise, have fun and share life with others, help and be helped in many ways. As a job it will help me financially, ergo open possibilities, allow me to travel and explore the world, settle down and have a family, etc... The most direct result is my choice to be an actor, then a better person, etc...
All three goals' results and ways of achieving are under great influence of our understanding of right and wrong, our genetics, upbringing, experience, etc...
Please disagree if possible and help me understand better. Thank you very much!