I don't know the exact history, but this reads as something that can't possibly be true. Had the "Irish shantytowns" successfully excluded other minorities? If so, how? Is there any "shantytown" anywhere on earth that isn't populated much more densely than 1850s Manhattan? What makes a "shantytown" not resemble a neighborhood? Not enough picket fences?

> Central Park was mostly a loose collection of shantytowns full of Irish people.

I wouldn't call a 50 year old neighborhood with 1,600 Irish and Black residents "not a large group of people". Calling that "not a neighborhood" is also an eyebrow raising population, especially given that Seneca Village had a large chunk of the (extremely rare) Black property owners in New York State.

You have to be careful repeating historical claims of an area being a "shantytown", as sometimes that is less a statement of fact and more of a way to justify a negative or prejudiced opinion. Given that the same people who called Seneca Village a "shantytown" also used slurs to described the area and called the residents "debased" and "wretched", there is reason to doubt the impartiality of those calling it a "shantytown".