The Hebrews were permitted to pass them on as an inheritance to the next generation until their debts were repaid, which is the meaing of ‘olam’ in Leviticus 25:46 (translated ‘perpetually’). The text does not mean they were permanent possessions, but is an explanation as to why they do not go out at the seventh year of release or the Jubilee as the Hebrews do (the reason being that their debts are not cancelled).

The meaning of olam isn't "until their debts were repaid". Here is how the word olam is translated throughout the Bible along with the number of times it occurs in parenthesis.

Ages (1), all successive (1), always (1), ancient (13), ancient times (3), continual (1), days of old (1), eternal (2), eternity (3), ever (10), Everlasting (2), everlasting (110), forever (136), forever and ever (1), forever (70), forevermore (1), lasting (1), long (2), long ago (3), long past (1), long time (3), never (17), old (11), permanent (10), permanently (1), perpetual (29), perpetually (1).

As you can see the vast majority of them mean forever or some synonymous word. The verses I quoted even said "slaves for life", not slaves until a debt is repaid.

Leviticus 25:39-54 makes a clear distinction between Hebrew indentured servants who voluntarily sell themselves to pay off debt and non-Hebrew slaves. Hebrew servants "are to be treated as hired workers", "must not be sold as slaves" and you "must not rule over them ruthlessly." They are to be released when they or one of their relatives have paid off their debt or at the end of 6 years of service, whichever comes first. Non-hebrews and women, on the other hand, were considered "slaves" and "property". They were "slaves for life" and didn't have the option of paying for their freedom.

However, the Law of Moses still maintained their personal legal rights relating to physical protection (Exodus 21:20-21, 26-27)"

Did you read those verses? The first one says if someone beats their slave with a rod they should not be punished if the slave survives the beating for a day or two. The second one is only about Israelite slaves as I mentioned previously.

Any bondservant purchased from the Gentiles had the right to flee their master, and receive the protection of the Law of Moses if they did so:

Deuteronomy 23:

15 You must not return an escaped slave to his master when he has run away to you.

16 Indeed, he may live among you in any place he chooses, in whichever of your villages he prefers; you must not oppress him.

Thus even for bondservants purchased from the Gentiles, servititude was not a permanent institution.

Neither of those verses or the surrounding verses say anything about them being gentiles. However, the following two verses and many other verses in the surrounding chapters mention Israelites, so given the context and all the other verses from Leviticus they are most likely talking about Israelite slaves.

Importantly, the Law of Moses made no provision for any slave trade. It was permissible to purchase men and women who voluntarily sold themselves into indentured service, but not to sell them (Exodus 21:2, Leviticus 25:39, 42, 45, Deuteronomy 15:12).

As I already said, those rules only apply to Israelites.

Taking men and women and enslaving them against their will, or selling them into slavery, was expressly forbidden on pain of death (Exodus 21:16, Deuteronomy 24:7).

The second verse specifically says "a fellow Israelite." The first one doesn't specify who it applies to but based on other verses in the Bible it's pretty clear that gods people have no problem kidnapping and enslaving people, so I think it's safe to assume he was referring to Israelites again. I already mentioned Deuteronomy 20: 10-15 where Moses himself tells his army to make an entire city into slaves and if they don't cooperate kill all the men and take the women and children as "plunder". If Moses was talking about Gentiles instead of Israelites in that Exodus verse you mentioned, then why would he command his army to do exactly what he just said not to do?

Here are some more verses where gods people force people into slavery.

Joshua chapter 9 talks about how Joshua and his army is going around slaughtering cities in the name of the lord, but due to some subterfuge by one of the towns he ends up forcing them into a lifetime of slavery instead of killing them.

King Solomon used forced slave labor to build "the lords temple."

1 Kings 9:15-22 - "Here is the account of the forced labor King Solomon conscripted to build the Lord’s temple, his own palace, the terraces, the wall of Jerusalem, and Hazor, Megiddo and Gezer. (Pharaoh king of Egypt had attacked and captured Gezer. He had set it on fire. He killed its Canaanite inhabitants and then gave it as a wedding gift to his daughter, Solomon’s wife.  And Solomon rebuilt Gezer.) He built up Lower Beth Horon, Baalath, and Tadmor in the desert, within his land, as well as all his store cities and the towns for his chariots and for his horses—whatever he desired to build in Jerusalem, in Lebanon and throughout all the territory he ruled. There were still people left from the Amorites, Hittites, Perizzites, Hivites and Jebusites (these peoples were not Israelites). Solomon conscripted the descendants of all these peoples remaining in the land—whom the Israelites could not exterminate—to serve as slave labor, as it is to this day.  But Solomon did not make slaves of any of the Israelites; they were his fighting men, his government officials, his officers, his captains, and the commanders of his chariots and charioteers.

Psalms 2:8 says "Ask of me (god), and I shall give thee the heathen for thine inheritance (slaves)."

Isaiah 50 says, "This is what the Lord says: “Where is your mother’s certificate of divorce with which I sent her away? Or to which of my creditors did I sell you? Because of your sins you were sold; because of your transgressions your mother was sent away."

This person was clearly not working voluntarily as servant. The slave isn't the one selling themselves, they are being sold by someone else as shown by the underlined part.