You're not wrong. But, human history goes back roughly 200,000 years. Slavery can only be dated back to 1860 BCE.

One could argue that the "bondage curve" -- if there is one -- is parabolic. I.E. human bondage peeked sometime during the Atlantic Slave Trade and has been going down ever since.

One could also argue that -- before modern machinery -- humans existed for nearly 200,000 years with no documented form of bondage.

I'm assuming (I don't know) the OP is referring to what some people call "modern slavery" -- in that the majority of the workforce has 0 social mobility. I think it's pretty absurd when people compare this to slavery during the Atlantic Slave Trade, but it happens.

Your arguments seem misleading - the existence of anatomically modern humans goes back roughly 200,000 years, but human history, i.e. the era with documented evidence starts with widespread writing that comes much, much later; first samples of writing is from ~5000 BC, but they're sparse enough to not be informative about social practices.

The very first documented law codes (2100–2050 BCE https://en.wikipedia.org/wiki/Code_of_Ur-Nammu ) already mention slavery. We can't know how long slavery existed before that, since those are literally prehistoric times and archeological evidence is not sufficient to determine these relationships, however, as the current evidence shows that slavery existed for as long as we have documented form of anything, there's absolutely no reason to assume that for the 200,000 years slavery didn't exist and good reason to assume that it did exist for at least part (or even all) of that undocumented time, as in the absence of any other evidence it would be prudent to assume that civilization at 10,000 BC had similar practices as it did in 2000 BC instead of being significantly different for no good reason from all other documented human history - we have no historical evidence at all of a time in early human history without slavery.

What part of those laws that didn't pertain to agriculture (failing to plant/harvest) were about the penalty for raping somebody else's slave. So many measures of grain etc.

That does bring the notion that we can make some assumptions about slavery in prehistoric times; it seems a core part of society in early agricultural societies but we have not observed it so much in hunter-gatherer communities (except sedentary hunter-gatherers with higher population density, which generally do have slavery, so it's more about the settling down rather than food source) - purely for economic reasons; it's practical/useful to keep slaves for farming or mining labor, but not so much for sparse, mobile hunting/gathering parties. Raiding neighbours for "wives" i.e. sex slaves does seem to be a thing even in those societies, though.

It could be a reasonable assumption that the prehistoric agricultural societies had slavery just as early historical agricultural societies, but that the earlier hunter-gatherers, i.e. a major part of those 200,000 years did not have widespread slavery. Well, other than the "intermarriage" with neighbours (often likely not fully voluntarily) which predates modern humans, given the genetic evidence for the partial "assimilation" of neanderthals and other parallel hominids.

Absence of evidence is not evidence of absence.