The GP's argument is that slavery was a given in many societies a long time before the printing press arrived. So, they're not even "concurrent happenings in history". We have references to slavery as far back as the Old Testament and Homer's Iliad.
I'd say the same thing about colonialism, the difference between the classical world (and earlier) and Europe post-1600 is the scale, not the practice.
Yes, an increase in the scale of slavery enabled by the commercial instruments (bonds and commercial insurance) that mitigated risk for the trade.
Whilst contracts had previously been written by hand, the standardisation and scale of reproduction enabled by Gutenberg meant that risk could be transacted in open markets by complete strangers.
I'd say the same thing about colonialism, the difference between the classical world (and earlier) and Europe post-1600 is the scale, not the practice.