Why did god allow people to be born after the fall ?

[SteveII]

I think involuntary slavery is immoral. The Bible does not say that slavery is moral.

The bible says exactly that involuntary slavery is moral. God even commands it and provides instruction for how it should be performed.

Regulating a universal cultural institution (shared by every nation in the region and probably on earth) is not the same as declaring it moral. You are inferring it--which is not the same as, well, either thing you said above.