Final answer:
The central truth in the Epic of Gilgamesh is the confrontation with death and the quest for immortality, underscoring the unavoidability of death and its role in defining the human condition.
Step-by-step explanation:
The basic truth mentioned as central to the Epic of Gilgamesh in the lecture Death, Loss and Reconciliation is the confrontation with the absurdity of death and the quest for immortality. Gilgamesh, after the death of his friend Enkidu, embarks on a journey to find eternal life, only to learn that immortality is beyond his reach. This epic asserts the inevitability of death and reflects on how one should live knowing that they will eventually die, which is intrinsic to the human condition and the Mesopotamian perspective on life.