" the reason USA and many other countries succeeded is due to openness to embrace diversity." - I'd say it was due to a combination colonialism of Asia, subjugation of Africa by the slave trade and world wars recking Europe. By 1950s, USA was already ahead of the rest of the world. Because it was in that position that it was able to attract immigrants which then helped to sustain its position.

There are many countries which are open to diversity - India would probably lead that list historically followed by modern Canada. But none is close to USA. On the other hand, Japan, South Korea, China and Asian tigers have done well without being open and diverse.