Please read your Bible. How many wives did David have? How many wives did Solomon have? The Bible was against marriage between spouses from different groups:
Ezra 9:1-2 And after these things were accomplished, the princes came to me, saying: The people of Israel, and the priests and Levites have not separated themselves from the people of the lands, and from their abominations, namely, of the Chanaanites, and the Hethites, and the Pherezites, and the Jebusites, and the Ammonites, and the Moabites, and the Egyptians, and the Amorrhites.
For they have taken of their daughters for themselves and for their sons, and they have mingled the holy seed with the people of the lands. And the hand of the princes and magistrates hath been first in this transgression.
and
Nehemiah 13:27 And shall we also be disobedient and do all this great evil to transgress against our God, and marry strange women?
Those people who were against interracial marriages could find support in the Bible. There is no single “original biblical” definition of marriage, since the Bible contains different versions of marriage.
But it does classify them by tribe/nation. “The Ammonite and the Moabite, even after the tenth generation shall not enter into the church of the Lord for ever” - Deuteronomy 23:3.
I suggest that you study the Bible more closely. It does not always say what you seem to think it says.
rossum