"Not the Fourth Amendment, but in the original text that ONLY gave the vote to significant landowners. Hmm..."
We were talking about the Fourth specifically. However, if you insist, the Magna Carta only gave rights to the barons, The US Constitution, as written, did not specify who was and was not allowed to vote. That little detail was left up to the individual states. Various amendments have, over time, limited State powers over who is, and is not, allowed to vote. See the 15th, 19th, 24th and 26th amendments.
"And the whole Three Fifths Compromise, too."
Repealed 'way back in 1868. No doubt you remember this happening vividly.
"What in the Bible were the Founding Fathers avoiding?"
The entire religion thing. But they weren't avoiding it, they were rejecting it outright.
"PS. If the Constitution really matters, why the push to enslave women to their wombs despite a little something called the Thirteenth Amendment?"
It's a control thing. Brainwashing is ugly both in progress and outcome.