states, not geographical units.

Because states are political units. If you don’t like the laws of one state you can move to another, and this extends to the state's voting power when choosing a president.

As to your innovation in voting, if you accept immutable aspects of identity as the basis for voting rights you're opening the door to some terrible ideas, like ethno-states and Jim Crow laws. Again, without embarrassment at the facetiousness, I'm also not sure how actually making the Jews have more power in 1930s Germany would've solved their problems. Would've probably fuelled grievances: "Hey, Adolf, you know that Jews really do run Germany?" Eeek!

The best way to protect minorities is by the protected freedoms of speech and to bear arms, not by weighting votes by arbitrarily chosen characteristics.

You can take account of everyone without pleasing them all. For example, in systems with run-offs or some kind of ranked choice, you need to appeal to voters who might not have you as their first choice, but whose second choice votes you need. That's better than being able to use a divisive strategy that appeals only to your base, and positively repels the rest.

The president isn't the president of “the people” but of the states. It says so right there on the tin: “President of the United States.”

Which means the president is and should be, elected by representatives of the states. The House of Representatives should be the only federal office directly voted on by “the people.” If that were the case, especially eliminating the direct election of senators, you’d see a much less divisive, gridlocked system where governance is more about public service and less about these election soap operas.