The page does not show that one-eyed giants were real.
Debated. The skull is from a real animal, not a one-eyed giant.
In Crete, remains of a Deinotherium were found. It was an ancient relative of the elephant, about 4.6 metres tall, with tusks about 1.3 metres long. Its skull has one very long opening for the nose, in the centre. The page does not give an age.
The page says no one can prove that skulls like this started the old stories.
People told this story.
https://www.ancient-origins.net/myths-legends-europe/cyclopes-0017369