Catholics and Baptists are both different denominations of Christianity, so all Catholics are Christian, and all Baptists are Christian, but not all Christians are Baptists or Catholics, though all Christian sects originated in Catholicism.
As for a majority of blacks being Baptist and Latinos being Catholic, this is all rooted in history.
The majority of slave owners here in the US were Baptists. They forced their slaves to go to their churches and to take Christian names and forced the Baptist church upon them.
Spain has long been a heavily Catholic country, at least since the middle ages, if not longer. It was the Spanish who went to Cuba and Puerto Rico and South America and Mexico. They colonized these places, destroyed the natives, etc.