The cultural divergence of Europe/UK & the US

Nothing progressive about the U.S. in 1923.

I’m from the USA but have lived in Spain and visit Europe as often as I can.

I've observed some of the cultural shifts you mentioned, notably that Europe and the USA have evolved differently since a century ago, with Europe seemingly emphasizing "tolerance/inclusion" more than the U.S. While I concur with some of your observations, the claim that the U.S. was unilaterally more progressive than Europe a century ago might require further nuance.

For instance, certain ideologies that fueled the Nazi regime, like eugenics and prison camps, originated in American thought and policy. Eugenics was “pioneered” by prisons in California, and the US had a dark history with the harsh treatment of Native Americans. Additionally, the U.S., one century ago, was grappling with significant social issues. The Jim Crow laws enforced racial segregation in the South, there were significant labor issues, and women were still fighting for their right to vote which they eventually achieved in 1920; later than many European countries like the UK, Norway, Denmark, etc.

In other words, while the U.S. did have progressive elements in the early 20th century, I’m not sure if it was categorically more progressive than Europe.

As for the modern perceptions of racism and inclusion, I noticed the same things you have; that on the surface, Europe appears to be more inclusive than the USA. However, what I’ve learned is that racism manifests differently in Europe than it does in the USA, and for outsiders it’s sometimes hard to see. For instance in Portugal I learned from African-Portuguese individuals that, although Portugal has decolonized, some ethnic Portuguese will still refer to Africans as "Portuguese," without mentioning Africa or the names of the African countries they are from. While this may seem inclusive and anti-racist to us in the USA, the African-Portuguese see it as the Portuguese attempting to still "own" their former colonies by erasing their African identity.

Ok, so although I’m unsure if the USA was ever actually more progressive than Europe in the past, I do 100% agree that in the modern era Europe is MUCH more humane and grounded in shared values/resources than the USA.

I think the reason the USA has fallen behind Europe is largely due to the founding of the USA being built on individualism. While the EU is still capitalist, they are much more collectivist than the USA. In other words; the current culture of the USA is the logical-end result of a country founded on an Anti-tax war that promoted rugged individualism.

The narrative that emerged from the American Revolution’s portrayal of King George III as a tyrant has played a large role in shaping American values & attitudes, especially those related to government, taxation, and individual liberties. These values & attitudes influence policy debates & decision-making to this day.

In 1772 England, the Somerset Case ruled that chattel slavery was unsupported by common law in England & Wales. This led to a degree of anxiety among American businessmen & slaveholders (English Heritage, 2022; Roberts, 2021). Their desire to maintain the institution of slavery was a significant factor in their decision to break from Britain, as emphasized in the U.S. Declaration of Independence where they accused King George III of inciting slave rebellions (1776). This desire to break away from England led to the monied interests & slaveholders creating an anti-tax propaganda campaign that painted King George as a Tyrant.
Indeed, to this day, the story of the American Revolution as taught in US schools places a strong emphasis on the idea of resistance to taxes & tyranny, a narrative that continues to shape Americans attitudes towards government, taxation, and public spending.

When you consider that American children are socialized to view the American Revolution as an anti-tax war against tyranny, & that over 55% of Americans view any public spending as “socialism” that “incentivizes laziness” (Pew, 2019) it makes sense that the USA would fall behind Europe in terms of a developing a more humane culture with a sense of shared values/resources, in other words, it’s embedded into the national framework of the country as “Unconstitutional” & “Tyrannical."

I can't really add much to VinceD's excellent response, except to emphasise that some of these issues may be baked right into the US constitution and its form of government.

The USA is often thought of as a 'young country', which in many ways (culturally-speaking) is perfectly true. But if we measure 'country' in terms of a continuous constitution, it's false -- the USA is one of the oldest in the world.

With European civilisation in ruins after WWII, most of the continent went through a constitutional/governmental overhaul. The (West) German Constitution dates back to 1949. The Constitution of the Fifth Republic (France) dates back to 1958. Etc. Etc. And, of course, the values embedded into those constitutions -- and the entire European Project [EU] -- reflected the 'never again' attitudes of the post-war period.

Even the UK, which doesn't have a written constitution, has evolved in the last two hundred and fifty years. Do we believe the Founding Fathers of the USA would have been stridently anti-monarchist against a modern constitutional monarch as the ceremonial figurehead of a parliamentary democracy? I don't.

And the USA's constitution was, of course, designed by Enlightenment era, lawyerly minds to be rigid and promote legislative gridlock (against tyrannical government) and individual rights. Perfectly sensible -- brilliant, in fact -- at the time. But how well does it fit with the modern world?

It's more difficult for the USA to make significant changes at a federal level. And this continues to be reflected in the US's mainstream culture. There's a certain clinging to that document, as if it is the final word on 'progress' -- as if the 'new' USA constitution and the values it represents is the progress.

the US a century ago was a leading innovative progressive culture

How so ?
Equal rights for blacks ? or women?
Banning alcohol? that was a radical move tbf

nationalism is still strong in parts of europe. we see it in russia and the balkans. the belief in conspiracy theories is becoming more mainstream in america.