The Indus civilization, flourishing around 2500 BCE over an area larger than Egypt and Mesopotamia, left thousands of seals covered in signs. But the inscriptions are very short, about five signs on average, and no bilingual 'Rosetta Stone' has ever been found. More than a century after their discovery, nobody can read them.
Around 2300 BCE, Enheduanna, daughter of King Sargon of Akkad, became high priestess of the Moon god at Ur. She composed hymns to the goddess Inanna and put her name to them. She is the oldest person identified as the author of a literary work, about 1,500 years before Homer.
Squeeze Earth's 4.5 billion years into a single 24-hour day. Homo sapiens shows up around 11:59:54 p.m., roughly six seconds before midnight. All of written history, from Sumerian tablets to today, fits into the final tenth of a second. A cosmic blink.