Black usually means the descendant of slaves. When Obama was starting his political career there was some debate in the Black community about if he really counted as Black, since he didn't really have much contact with the Black community until his 20s and his history is quite different.
White typically means descendants of various waves of settlers with limited ties to any specific European country. Generally they can trace their lineage to a mix of early and later arrivals. With a strong bias towards northern Europe.
Hispanic generally meant Mexican, Cuban, or Puerto Rican. Which were fairly geographically distinct communities in the 90s so one word for all three didn't cause much confusion.
Hispanic is a newer term, minted during my lifetime. I know older people who used to be white until they were relabeled as Hispanic.
https://daily.jstor.org/where-did-the-term-hispanic-come-fro...
https://www.history.com/news/hispanic-latino-latinx-chicano-...
"For many people, Black reflects a shared sense of identity and community. White carries a different set of meanings; capitalizing the word in this context risks following the lead of white supremacists."
I don't find that thoughtful.
The argument further erodes when they also capitalize "Asian", which is described as "groups that include myriad ethnic identities united by shared race and geography and, to some degree, culture" - How does that not apply equally to "white" also?