As for slavery in the Bible, especially in the Old Testament, you're dealing with a society that had no coinage or money in the form we have it today. As a result, labor contracts tended to be lengthy, the equivalent of what today we'd consider slavery or peonage.
They were not 'labour contracts'.
Leviticus states that slaves may be purchased, treated as property, their offspring treated as property and passed to your children as a 'permanent inheritance'
That is slavery.
On the matter of Hebrew slaves, the male slave may go free after seven, but his wife and children (if gained during that time) cannot go free. That is a forced choice. And no loving man would choose it, therefore he becomes his masters property forever and is branded.
That is slavery.
A female slave that does not 'please' the man that bought her can be bought back again.
That is sex slavery.
And that's before we get to Jesus.
Don't bullsh-t with the 'it's not really slavery' argument
It is.