Preferably nonexistent. Not all worlds need to have crazy humans like we do.

Indentured servitude - The age old question of what to do with the one who cannot pay their debts? If they are killed you don’t get it back, if they are punished in a way they cannot work you don’t get it back. So instead they are offered a payment plan of providing their creditor a certain amount of labour.

Serfdom - generational bondage to the land. Not belonging to the landowner but to the land and the obligation to tend it. The more common the worship of the Earth Mother and her thousand daughters are the the more sacred this duty becomes. Some legal systems recognize the serfs possibility to move, but only if they find someone else deemed of similar of better quality to take over the land.

Work as rehabilitation into society and paying one’s debts to it - This was a spur of the moment choice I made in one game where a player or two went straight to execution for crimes. But that didn’t jive with me so instead it is a more common practice for criminals to pay off their debts to society through work while undergoing rehabilitation and reintegration. Also prisons are expensive, unless we are talking about inhuman stuff, so them not being a financial black hole helps keeping them human.

Chattel slavery - only if I want to showcase a culture as vile to the bone pretty much without any chance of redemption.

Then we can get into the issue of raising, trading and slaughtering livestock as the difference between the soul in a beast and a human is that the beast is much more strongly affiliated with the Beast rune. But in essence they are the same. And yes that leads to widespread veganism and/or sacrifices to and worship of the Mother of Beasts.