If I may add a little to what you correctly stated...
When I was in the Air Force, I deployed to Morón Air Base. Morón de la Frontera is less than 20 miles from Sevilla, which is smack-dab in Andalucia. Puerto Ricans (for one,) are mostly descendants of Andalucians.
PS: Andalucians do NOT consider themselves to be equivalent to Castillians, who are different from the Gallicians, who are very different from the Basques...the folks in Spain are very territorial about that.
I’ve heard people call Old San Juan more Andalusian than Seville itself!
You are right, in aspect manners, customs and culture, PRs are mostly Andalusian, and the “minority” here who are descendants from the Castillians, Basques, Galicians, etc. of Northern Spain are the “blanquitos”.