The Old Testament, of course, was just documenting the prevailing convention. This stuff goes waaaaayyyy back.
As anti-Israel as I am, and have long been, I never attributed to them the origin of overkill. It's just a convenient subjugation method used by humans the world over. I have no doubt the Innuit, the Maya, the Mongols, and every other empire used it any time necessary to intimidate and subjugate. Kill hope, and assimilation becomes the alternative.
One of my middle eastern friends explained their concept of revenge as, "You kill one of us, we kill your entire family". It is the antithesis of American short memory, "Let's move on" culture.
We get many things wrong in America today. But, to our everlasting credit, we did indeed lead the world ahead when we rebuilt Japan and Germany. Yes, it was in our economic, military, cultural, and political interest, but all that does not negate the wisdom of being a merciful victor. We look on our Japanese and German allies with pride, knowing our values are very different in many ways, but respecting the accomplishments of great nations overcoming their terrible mistakes.
Biden did the right thing by condemning terrorism and trying to toe the line of "We support Israel and we condemn Hamas". Biden is no fool though, and he knew he was dealing with a snake when backing Netanyahu. If he didn't already know this from his days in the Senate, he would have known if from the way Netanyahu dealt with the Obama National Security Team and even Obama himself.
It is a testament to Obama that he didn't take revenge. It was within his power, as foreign policy is much easier to effect than domestic for a president. Like JFK, Obama was unquestionably underqualified in experience to be at the top, but I'm still glad I voted for his election and re-election. It was more important to put him there than for him to be successful across the board.
I don't know how Biden is going to get himself out of the Chinese finger puzzle he's gotten us into. Two things might save him: the world's horror at what is happening in Gaza and the shit that the Israeli economy has turned into because they have called up so many workers to military service. Well, and maybe Netanyahu being sent to prison.
I'm no Biden fan, but I don't fault him for the position. He inherited a nation and government that has been relentlessly and irrationally pro-Israel. This policy should have ended way back in the Carter Administration, but didn't. The ascent of Christian Fundamentalism ensured it could not. Ironically, Carter was a Fundamentalist, but didn't confuse his religion with his Consttitutional oath of office, and he rebuffed the Moral Majority and other wingnuts who thought they'd exploit his affiliation. That helped get him voted out.
But, Biden could have signaled to the Arabs that America would not support the war once the bombing started and towns were levelled. He did not.
We would have been wise to let the enemies know that they would not be attacked by us if they bombed Israel in return. But, treaties don't allow it.
I'm not sure Biden had a good hand to play. But, if he were not running for re-election, I don't think he would have done as much damage as he has.
As it stands now, we have a very real probabilty of a Mid-East War that will become a conflagration.