The categories into which I would divide Giants are as follows:-
(a) Mythological Giants These would mainly be Giants remembered from their encounters with gods and would include such beings as the gods of Greek and Norse mythology. These are often on an equal footing with the gods and will sometimes intermarry with them. They should not be regarded as likely to preserve any reminiscence of real gigantic humanoids.
(b) Etiological Giants These are Giants believed to have been transformed into geological features. Mount Atlas, turned to stone by the Gorgon's head would be an example. Once again, these cannot be used as reasonable evidence for the existence of large humanoids.
(c) Ordinary Giants These would simply be taller than the people recording their existence. A small person of Mediterranean origin encountering a person of Norse origin might describe him as a Giant.
(d) Category Four These are Giants preserved in oral lore. These could mean that the groups in whose lore they feature might well have encountered large unknown humanoids/anthropoids in days agone and may even still be encountering them.