It's easy to argue even when you don't ignore it. Just because you're worried about a bully doesn't mean you're not one yourself; they're not mutually exclusive options. The Founders were hardly paragons of virtue, but to imply that their sole interest, as a collective whole, was to oppress the non-white non-male non-landowners is patently absurd.
Was that the primary interest of some? I have no doubt. Did the thought of protecting that interest happen to align with the interests of the people who were looking to protect the country from the abuse of a tyrannical government? In this instance, it sure did.
The Constitution (like the Articles before it, though less so) made it intentionally difficult to to Amend out its inherent protections. Did that also "bake in" some of the unfortunately common abuses of the time? You bet. But it's also led to a history of the following nearly 250 years in which the list of protections in the Constitution has greatly increased as the framework of those abuses has eroded.
At least until very recently, of course.
You can argue whether or not the higher bar for an Amendment is a good thing or a bad thing, but trying to say that "it's solely because of slavery" is just as wrong as saying "it had nothing to do with slavery".
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You literally got this far before being hopelessly wrong.
Grats.
Edit: Hah, it got worse from there.