Legend compresses many people into one enormous figure, and the giants are what that compression looks like from the far side of time. Generations of the formidable, the ancestors who did more than their neighbors, get gathered by collective memory into single larger-than-life shapes. The ordinary is burned away, and what remains swells into myth. History cannot be told without this. The past is remembered at the level of selection, and selection turns a hundred forgotten strong men into one man of renown.
These figures are not lies. They are the distilled heroism of what a people admired, drawn from countless faded lives and held up where it can still be seen. Understand that the mighty men of old are your ancestors made visible, the best of them concentrated into a form memory could carry. The giant is what greatness becomes once time has done its editing.