Why doesn't the bible condemn slavery?

Many Christians and Christian apologists claim that the bible is an objective source for morality which is immutable in its righteousness and divinity.

How can this be true when the bible has numerous passages that fail to condemn, and in fact outright justify slavery?

One common rebuttal to this is that somehow slavery in the ancient world was different from the slavery of the American pre-civil war south. However, on close inspection this notion falls through.

Claim: Biblical slavery was different because it only constituted a limited timeframe and was for repaying debts.
The Bible: (Deuteronomy 15:12-13) 12 If any of your people—Hebrew men or women—sell themselves to you and serve you six years, in the seventh year you must let them go free. 13 And when you release them, do not send them away empty-handed.
This only applies to people who were Hebrew, and not to people who were from other tribes or cultures. This worked to reinforce the race-based slavery of the US south by justifying blacks as "others" so it was morraly right in their eyes.

Claim: Most ancient cultures practiced slavery, but the Hebrews had laws limiting the amount of suffering for slaves
The Bible: (Exodus 21:20-21) 20 “Anyone who beats their male or female slave with a rod must be punished if the slave dies as a direct result, 21 but they are not to be punished if the slave recovers after a day or two, since the slave is their property.
The US south also had "slave codes" which prohibited mistreatment of slaves, including killing them. https://en.wikipedia.org/wiki/Slave_codes ;

Claim: Slaves to Hebrews were recognized as human beings and were dignified, unlike slaves in the US south
The Bible: (Job 31:13-14) 13 “If I have denied justice to any of my servants, whether male or female, when they had a grievance against me,14 what will I do when God confronts me? What will I answer when called to account?"
This claim is superficially vacuous, because the very concept of slavery defies human dignity, which is why modern humanism rejects slavery outright.

Claim: Jesus was opposed to slavery
The Bible: (Matthew 18:21-35), [parable of the unfaithful servant, absent for brevity] (Matthew 6:24) 24 “No one can serve two masters. Either you will hate the one and love the other, or you will be devoted to the one and despise the other. You cannot serve both God and money.
Jesus tells several parables, and at no point in the text explicitly condemns slavery as wrong in god's eyes. He even refers to the relation between god and man as one of master and slave, insinuating that it is our moral duty to do as god commands, suggesting that it is appropriate. Latter texts do little to condemn slavery, providing fuel for both slaveowners and abolitionists alike.

Claim: Judeo-Christian teachings helped to eliminate slavery
The Bible: (all of the above, plus a lot more I didn't list)  (Genisis 9:18-27) https://time.com/5171819/christianity-slavery-book-excerpt/ ;
The fact is, that the single contribution to western society that was not seen in other cultures or which can be attributed to a different system of thinking is racial slavery. No other culture discriminated in who they made slaves, however the bible worked to reinforce racial slavery and has a continued legacy to this day. The claim that slavery was ousted by Judeo-Christian values (a term made up in the late 40's) is simply false.  The reality is that economic and technological developments made paid labor cheaper than slave labor, contributing to the industrial power of the North which conquered the rebel army in the south. Today, a tractor can do the work of 100 slaves and costs about the same when adjusted for inflation. It was science and technology, not Judeo-Christian values which eliminated slavery.

Hope that clears this all up, but I doubt it will. Christian apologists cling to their beliefs like stains in toilets.