The Bible does not prohibit all intermarriages
We are not Bible Jews. We are Rabbinical Jews. The Torah only forbids intermarriages with certain non-Israelites, not all of them. But at least since the days of Ezra and Nehemiah, Judaism has forbidden intermarriages with non-Jews who have not converted.
There are many verses that proscribe marriages with non-Israelites, but until the time of Ezra and Nehemiah, the prohibitions only pertained to marriage with idolaters. Deuteronomy 9:3, for example, has Moses warn the Israelites who are about to enter Canaan and encounter idol-worshiping Canaanites that the Israelites must completely destroy the Canaanites. Moses also said: “Do not give your daughters to their sons or take their daughters for your sons.” What is significant is that the Torah could have prohibited all intermarriage at that time as well as in the other books of the Five Books of Moses, but it only restricted intermarriage with the Canaanite idolaters.
There are similar restrictive prohibitions in Genesis 24:3, Exodus 34:16, Joshua 23:12, Judges 3:6 and 14:3, and I Kings 11:2, which do not prohibit all intermarriage. It is not until Ezra spoke against intermarriage in 9:2, 12, and 10 3, and Nehemiah did so in 13:23-27, that there was a blanket prohibition.
Not only is there no biblical prohibition, many of the early Israelites, including their leaders, including Moses himself, married non-Israelites; Moses married the daughter of a Midianite priest. According to the Talmud, Moses’ successor Joshua married the Canaanite woman who saved the two spies that Joshua sent to Canaan and the descendants of that union made great contributions to Judaism. The patriarch Jacob married Leah and Rachel, who were related to him, but he also married their two maids who were not related. Jacob’s son Judah, the ancestor of King David and the messiah, married a Canaanite. Boaz, another ancestor of King David, married Ruth a Moabite. King Solomon, David’s son, married the daughter of the Pharaoh of Egypt and hundreds of other non-Israelite women, and the Bible does not criticize him for the intermarriages, but that in his old age, his wives turned him to other gods. Rehoboam, son of King Solomon who followed him as king, was the son of Solomon and a non-Israelite woman. Joseph, son of Jacob, married the daughter of an Egyptian priest. The judge Samson married a Philistine. And there are many others who did likewise.
All of this is interesting, but it does not dilute the prohibition against intermarriage in any way. It emphasizes that Jews today are Rabbinical, not Biblical Jews.
 The Torah had a strong inexplicable dislike of Canaanites. The dislike is first mentioned when in Genesis 9:20-27, Noah’s son “Ham, the father of Canaan, saw the nakedness of his [drunk] father, and told his two brothers” who covered him. When “Noah awoke from his wine, and knew what his youngest son [presumably Ham] had done to him, he said ‘Cursed be Canaan!’” The Torah gives no reason why he cursed his grandson instead of his son Ham.
 We do not know the dates for Ezra and Nehemiah. It is generally presumed that they lived in the mid fifth century BCE.
 They were concubines, but the Talmud states that concubine was a type of marriage and most importantly, their children were the leaders of several of the twelve tribes.
 I Kings 11:4.