Namma - Claims to be creator of mankind, 'mother of everything'.

Namma (also read Nammu) is a very ancient Mesopotamian goddess, associated with the city of Eridu and counted among the oldest generation of Sumerian deities. Her name is written with the sign for "(cosmic) subterranean waters," and one scholar has called her the "Cosmic Ocean." In later tradition she was regarded as the primeval sea from which the cosmos emerged, and from the Old Babylonian period onwards she was considered the mother of An (Heaven) and Ki (Earth).

In the myth Enki and Ninmah, she is called the "original mother who gave birth to the gods of the universe." There she is also the one who conceives the idea of creating humankind and rouses her son Enki to carry it out. Despite her importance in the creation stories, very little mythology about her survives, evidence for a cult is scarce, and in later Akkadian texts she is rarely mentioned. In later tradition, Tiamat took over her role as the primeval ocean.

Scholars disagree on some points. No explicit text equates Nammu with the sea, and one recent study suggests she may have represented groundwater. The reading of her name is also debated, and "Namma" is now the more commonly accepted form.

Sources
1. Nicole Brisch, "Namma (goddess)," Ancient Mesopotamian Gods and Goddesses (Oracc), 2024: https://oracc.museum.upenn.edu/amgg/Listofdeities/Namma/index.html
2. Wikipedia, "Nammu": https://en.wikipedia.org/wiki/Nammu
3. EBSCO Research Starters, "Nammu (deity)": https://www.ebsco.com/research-starters/religion-and-philosophy/nammu-deity

The Oracc entry is the most scholarly of the three and is a good one to cite.