Indeed, the two-party system is a stilted one and it precludes certain political options from the outset. However, the Republicans are notorious for moving further and further to the right, so Americans have effectively gotten more than two options over time. The modern Republicans have always stood almost entirely for the wealthiest business class, and they used to be free marketeers before the cult of Trump.
The Democrats have been much less principled than the Republicans, so since at least Bill Clinton’s triangulations they’ve moved to the right along with the Republicans, up till the point of the neoliberal centrist consensus. That universal rightward move in the US demoralized young people, blue-collar workers, and leftists, which largely cost Hillary Clinton the election. Young people don’t vote, though, which cost Bernie Sanders and Warren their chances, in turn.
I notice that to make up for the lack of “full-spectrum” representation, party defenders speak of the different “wings” of their party and of how theirs is a “big tent party.” That must be a largely rhetorical move, though, since the party has to work towards enacting a unified platform. So the ritual is typically for the candidate to lean leftward or rightward during the campaign, depending on the party, and then to lean in the opposite direction towards the center during the election, to appeal to moderates.
Mind you, that’s changed since at least George W. Bush, since the Republicans realized the rigging of the Electoral College enables them to win just by appealing to the minority of voters who comprise their rabid base. Thus, the GOP has eliminated its moderates and moved ever further to the right, giving the world the dark miracle of President Trump.
As for where the economists stand in all of this, it’s not with any set of objective facts, since economics is a pseudoscience. They go largely where the money is. But economics has also been as politicized as the Supreme Court, so there are liberal and conservative economists, to suit each party platform, and never the twain shall meet.