When people first encounter myths at a young age, they often sense that something is true about them. As they learn more about the world, people realize that the myths they grew up with are not literally true. But the myths very often turn out to hold truth metaphorically. The myths are early literature, and like other literature they tell truth in a mode that philosophy and science cannot, since they embody the truth through accounts of specific living beings. Some topics, such as love and family relationships, are perhaps more truly explained through this mode and the perspective of specific individuals.
Another way of explaining this point is to say that literature and philosophy need one another to provide full explanations of human experience. On such points, see Martha Nussbaum's excellent book Love's Knowledge. People tell stories all the time because stories are meaningful ways to get across the realities of human experience. If we were to insist that no one may give credence to anything not given in the terms of science and logic, our discourse would be greatly impoverished.
If Freud is right, myths like that of Oedipus express what is normally inexpressible about the human condition, such as the young child's feelings about his parents. The most unlikely scenario may turn out to be generally true about us, if we only let ourselves encounter the inexpressible and face the taboo. On a more mundane level, most everyone can understand the feelings of family members who grieve over the loss of a parent, sibling, or child, and there is a sense in which the extreme reactions of these family members reflect the truth of what grieving persons might really want to do, even if, in a saner moment, they never would choose to take their grief to an extreme.
Even the mythical accounts of nature express a sort of truth. Winter's dark and cold months are expressed well in the myth of Persephone, whether or not she is really in the Underworld and Demeter is grieving. Yes, we know already that winter is this way, at least at Greek latitudes, but that does not make the myth less true in the telling. Likewise, that echoes exist is true, and whether or not we have ever heard an echo across a canyon, the myth tells us something we truly can expect about nature.
There is much that is false about myths and about all fiction by nature. There is a famous ancient quarrel between philosophers and poets. Nevertheless, we would not be reading the myths today if they had nothing lasting to offer us.
