The Israelites didn't completely wipe out the Tribe of Benjamin because they had pity I guess, they been through a lot together (fighting wars, etc). So they spared them by giving them some captured women so they wouldn't die off. But again, it was not allowed for the other Tribes to give any of their daughters to the Tribe of Benjamin (they were cut off).
Still skimming through. Things make a lot more sense if you read the Bible when you're older. Also the English Standard Version is a lot easier to digest.
A couple Benjaminites raped a concubine all night that belonged to the Levites, the other Tribes got pissed because the Benjaminites wouldn't give up the perpetrators, then it snowballed from there.
(Judges 19:10–28)
Judges 21:6
Now the Israelites grieved for the tribe of Benjamin, their fellow Israelites. “Today one tribe is cut off from Israel,” they said.
Judges 21:7
“How can we provide wives for those who are left, since we have taken an oath by the LORD not to give them any of our daughters in marriage?”
Was not restored, read the verses you provided.
Israelites swore an oath, and God gave the Israelites victory over the Benjaminites. They were allowed to live because they felt pity, hence why Israelites gave them 100 virgins from outside of the tribe. Otherwise they were cut off from Israel from their daughters aka their wealth (through marriage) from future conquests.
It's quite straight forward. Only ones misinterpreting are the Jews trying to rape their way into Ancient History and act like some hot shit that they are definitely not.