Because the votes are not at all a representation of the country. The country is actively hostile to voters, particularly leftists. This means that a disproportionate number of votes are from conservatives, because the stats say that they would never win again if voting was actually fairly accessible to everybody. Combine that disenfranchisement with the disillusionment in both the system and the Democratic party, and it’s easier to make sense of how Trump won this last election despite getting less votes than he did the last time that he won.

I would say that your second point is more or less correct. Trump got less votes than his last term, but the Dems lost even more votes for various reasons. From running an unpopular candidate to running on a platform that largely consists of leaning more and more conservative year after year to gagging their actually popular candidates, leftists are fed up with the Dems.