Yes, some immigration is good. That doesn't mean all immigration is good. Are you willing to identify positive traits and limit immigration to those with those traits? Or do you balk at being selective? The defense of immigration always treats immigrants as one undifferentiated lump. But this is just the lumping fallacy.

>The "homogenous countries" started 2 world wars, one of them to "preserve their culture, ethnicities, identities". Would this not support the worldview that immigration has net benefits?

Oversimplification to the point of bad faith

>Also, can you explain how ethnic cleansing preserves culture and identities?

Obviously a disingenuous question