The origin and age of the figure are unclear. It is often thought of as an ancient construction, though the earliest mention of it dates to the late 17th century. Early antiquarians associated it, on little evidence, with a Saxon deity, while other scholars sought to identify it with a Celtic British figure of the Roman Hercules or some syncretization of the two. Archaeological evidence that parts of the drawing have been lost over time strengthen the Hercules identification. The lack of earlier descriptions leads modern scholars to conclude that it probably dates from the 17th century, and perhaps originated as political satire.

https://en.wikipedia.org/wiki/Cerne_Abbas_Giant