There is a rather simple model for understanding the human experience.
In our experience of the world and its phenomenon, there are are always two strains or flavors evident to us. Every "object" that enters the field of our awareness carries a kind of positive or negative magnetic charge that creates either a feeling of pleasantness in some degree, or a feeling of pain and unpleasantness in an opposite degree.
These positive and negative lenses, through which we perceive the world of the mind, pretty much inform everything we do, everything we aspire to. Virtually all of human behavior can be understood in terms of pursuing pleasantness and avoiding unpleasantness. At the end of the day, it is the basis of all science, all religion, all culture, all instinct.
In this, at least, Freud was correct when he suggested a pleasure principle as the driving motivation for human experience.
Pleasantness and unpleasantness——happiness and unhappiness---come in a thousand different degrees and flavors, and are described by thousands of different names. The experience of unpleasantness, for example, can be described as mildly as "restlessness," or as boldly as "loathing." Pleasantness can be simple "satisfaction," or as all-consuming as "bliss."
Close examination of our experience will reveal that every phenomenon born into our awareness carries some portion of a positive or negative emotional charge. The Buddhists will say that there is also feeling that is entirely neutral, but I'm not sure about this. It's true that some experiences don't really elicit much in the way of either longing or aversion, but looking closely at these moments it seems to me that the positive and negative are more or less balanced at these times——not missing altogether.
There is, I suppose, some scientific support for this, as modern physics describes negative and positive charges to the basic workings of matter & energy. Perhaps our subjective sensation of pleasantness and aversion is really nothing more than a manifestation of that truth of physics.
In any case, I think that when cavemen first recognized that faculty of awareness in themselves, it was the awareness of pleasantness vs. unpleasantness that was the primary mystery, and was probably more mysterious than life and death itself. The experience of pleasure and pain, after all, usually seems connected to our actions, at least in part, while life and death are largely outside our control altogether.
So I suggest that religion, science, culture, etc,, aren't about understanding the mystery of life, but rather the mystery of happiness and unhappiness.
All the mythologies of religion, for example, seem to me to be stories and characterizations revolving around the dance between positive and negative, happiness and unhappiness. To "God," we attribute the causes and origination of happiness, while "Evil" is the king of all that seems to be the source of unhappiness. This explains why evil is different for every person. In the experience of war, for example, nobody in the conflict ever cheerfully admits that they are serving the cause of evil. Evil always lurks in the other fellow, they guy who is compromising my happiness.
Religion is ultimately an effort to understand happiness and unhappiness, to court one and escape the other. Buddhism states this quite boldly as its intent; other religions dramatize it through elaborate mythologies.
Similarly, the working of science, government, art & culture, seems to be mostly driven by the mystery of happiness and unhappiness. Many governments, for example, use the idea of "the greatest good for the greatest number" as their driving principle. Science, at the end of the day, is about improving our health and comfort, and eliminating discomfort. Art seeks to articulate the drama of happiness and unhappiness, and ultimating to foster happiness through the creation of beauty.
Happiness and unhappiness exist nowhere but in our selves, our subjective experience. No outer physical event in the world is inherently good or bad. A terrible thunderstorm may be bad to a person caught out in the rain without any shelter, but it is good to the farmer longing for rain to quench his parched fields. It is entirely relative and subjective.
Good and bad, happy and unhappy are also slippery qualities. It's very common, for example, to pursue some activity that ostensibly seems to be happy-making, only to find that it's long-term effect is to create unhappiness. LIkewise, it's common for experiences of present unhappiness to prove to be long-term causes of greater happiness. So a well-lived life is very much about studying and evaluating the causes of genuine a happiness, nurturing those causes and weeding out the obstructions. It is a life of intelligent experimentation and observation. Hence, a man given to hedonism early in life may realize that a more genuine happiness comes about through a somewhat more ascetic approach to life.
Good and bad, pleasant and unpleasant, happy and unhappy exist only in the matrix of our awareness. If a phenomenon is extricated from the context of our awareness of it, it is entirely empty of such judgments. So it is the field of awareness itself where the science and study should be aimed. God is not in his heaven, nor the devil in Hell. Neither do they exist in other people. Only within.