Of course the US Senate is incredibly undemocratic and was set up to cement the power of the wealthy against people wanting to do stuff. It sucks. But at least I can understand the rationale given by people who would defend it. The 13 colonies were distinct entities, and the Senate was structured (on paper) to represent the interests of these distinct entities.
But every single state other than Nebraska has a "House" and a "Senate". And as far as I can tell, the Senate district boundaries are completely arbitrary. So what's the point?! No state other than maybe ones like CA or TX could have distinct subdivisions. It's either pointlessly redundant with the state House or broken up by a weird map that only serves to gum up the works (though I guess that's the point).
There in no excuse in 2023 for a form of government other than everyone's vote counting equally (with a possible exception for overweighting the votes of marginalized peoples, but that's such a far out possibility there's not much point in bringing it up). I can explain in detail how the Cuban electoral system is way more democratic than the US to an American, and they will just shut down and insist our system is more democratic regardless.
Any honest political scientist would tell you it doesn't make sense, especially on the state level. The best argument I've seen for bicameralism is the Soviet system's congress of nationalities, but that allows for ethnic representation rather than arbitrary geographic representation
You already know that the system lets wealthy people have their own mini fiefdoms, which is probably the reason most states use it