they were pissed that rich white landowners had insufficient say in how their govt runs
so they wrote stuff to give themselves the vote
(and wealthier areas with many slaves got extra weight to their votes)
and they were deathly afraid of mob rule and populism (which might be too disruptive to the social order with them on top)
so everything was a few degrees indirect
you vote for people who then voted for the real people
i think even house of representative candidates were chosen by state govts, so it's not like you could just decide to run and fill out paperwork