I always thought it was people from Latin America that were descended from people of those countries, but it's hardly easy to trace that anyway. Equally, I don't understand the difference between Latino and Hispanic. I always thought those demographics were more or less the same.
In answer to the OP, I think it stems to how the slave trade operated in the US compared to other countries. Although whether this is actually the case I don't know. Coming from the UK, bizarrely I'd say most Brits (including me) know more about the US slave trade than our own. Hard to say but in the Uk the main social conflict always seems to be more rich v poor than in the US where it's more centres around race.
It was about rich vs poor here in the US in many respects, even residing over racial divisions at certain points.. The Occupy Wallstreet movement a mere 5-6 years ago exemplifies that. There was a pretty big backlash against banker bailouts and the like, Bernie somewhat exemplifies that to, the short-lived Ron Paul phenomenon somewhat. This is the type of liberalism I tend to subscribe to, while I fully reject the Hillary brand of limousine liberal, Hollywood, identity politic left (whatever you want to call it) that seems to have almost fully taken hold over the more blue collar, class-based type.
I don't know what the hell happened in the last 4-5 years - don't know if the money masters and bankers got together and decided "alright, the masses are coming together and turning on us, can't have it.. Let's reignite race wars to take the heat off us!", or if people just got sick of fighting over wealth all at once and felt it more suitable to fight over race/identity.. but I noticed very clearly a very rapid change of things shifting from class, economics, war (things that mattered to me) and towards race wars.. Bernie was sort of the last gasp of that movement, until the identity politics focused candidate (Hillary) was, unsurprisingly, pushed to the forefront.