halbhh
The wonder and awe of "all things".
I don't get the logic in what you are saying and also don't think it is correctly understood in regards to the bible, besides as I already said, as a good saying, which hold no meaning.
The reason I don't follow your logic, is that if your explanation should be reasonable, the word slave should not appear at all.
The mere fact, that one person is identified as a slave (lesser) than another, demonstrate that the slave owner is not willing or interested in being treated equally to the slave or even being referred to as such.
I don't go grab someone off the street and make them my slave and tell them this saying and then expect them to reply... "Well, fair enough, it make sense, you are treating me fair and all, guess its ok to be your slave then, how generous of you to enslave me."
The logic doesn't work as I see it. And we can't deny that the bible is filled with rules about how to treat slaves, how they are your property and that you can beat them senseless, if you desire. All which is sanctioned by God. And it is even pointed out that God believes that hebrew slaves should be treated differently than other slaves, so even here the saying doesn't seem to be something God agrees with.
One way the saying could have meaning and at least be somewhat consistent, is if Jesus were referring to how the Jews ought to treat each other, as that would be consistent with what God said in the OT.
What is the essence of slavery?
It's to take advantage of someone, such as by stealing their labor, or time, or energy, or the things they have made.
So...therefore, logically, even if the simple form of slavery is outlawed so that it becomes rare (still around, but hidden)....that would not mean the more subtle kinds of slavery that no law talks about have become rare.
More subtle ways of taking advantage of others can continue everywhere, and have.
So, not only has slavery itself continued (even in the U.S.), but if anything, once you include all forms of taking advantage of others, the more general essence of slavery is even today common in reality, here in the U.S.