like you said, the hero of Wind isn’t known to be related to the hero of time, but given how we don’t know who his parrents are, its a small possibility that he might be.
also, the “related” theory do also make it possible that one of the Hero of Time’s desentants could be a girl which would be a good way to make “Linkle” a canon member of the Legend of Zelda lore, because its really lame if all of the desendants of the hero are boys only, though if the hero of wind is a decendant from the hero of time, then technicly Aryll would be the first (though unofficial) female “link” in the franchise, the reason i say unofficial is because she never takes the role as a heroine because of her age in WW.
however the theory does make the “Links” from the fallen timeline into a group of look alikes who all just happend to look and have the same name as the hero of legend… though it might have been like how all the princesses from the Legend of Zelda timeline are named Zelda, as in the parrents of all these “Links” from the fallen timeline named their sons after the hero of legend, probably as a hope of good fortune or something for their children.