The united states senate was a bad idea from the start. At the Constitutional Convention in 1787, populous states like Virginia supported the idea of a unicameral national legislature, with representation based on the population of each state. That’s the kind of system one would expect in a representative democracy.
But less populous states like Delaware and New Jersey wanted a unicameral legislature in which all states would enjoy equal representation regardless of population, which is a system one might expect of a confederacy or a conglomerate of independent sovereign nations.