Nin-me-sara, the Exaltation of Inanna, is attributed to Enheduanna, daughter of Sargon of Akkad and high priestess of the moon god at Ur, active around 2300 BCE. If the attribution holds, she is the earliest author in world literature whose name is attached to their own work, roughly a thousand years before Homer.
The hymn is not a decorous liturgy. It is a first-person plea in which the speaker names herself, describes being driven from her office by a usurper, complains that her prayers to the moon god have gone unanswered, and turns to Inanna instead, praising her power at length and asking for restoration. The composition includes the famous line in which the speaker says she gave birth to the hymn during the night. It is also a piece of theological politics, elevating Inanna to a position at the head of the pantheon in a way that served her father's unification of Sumer and Akkad.
The attribution is contested, and on reasonable grounds. The hymn survives in over a hundred copies, and they are Old Babylonian school tablets from roughly five centuries after her lifetime, made by trainee scribes. No third-millennium copy exists. Some Assyriologists therefore treat the ascription as a later tradition attaching a text to a famous historical figure, which was a normal ancient practice.
That Enheduanna existed is not in doubt: a calcite disc bearing her name and image was excavated at Ur, and administrative texts refer to her office.