I’ve heard this hypothesis before. It’s interesting to think about. I definitely don’t think they could have been referring to Neanderthals when they talk about “giants”-if that is even the correct interpretation. Neanderthal people were shorter than us on average although very, very stocky. Our ancient hunter/gatherer Pleistocene ancestors had far more in common with Neanderthals than they do with modern people. Even though we are the same species, culturally the Neanderthals were really not that different from them. If the Jews are the children of God, then perhaps the Homo sapiens of hunter gatherer times were the children of men. Maybe even everyone who wasn’t of their faith.