To understand much of our language, Gnorts would have to already be aware that our words and symbols gain meaning from how they're used, and you couldn't, for instance, determine that a swastika is offensive (in the west) by its shape alone.
In this case, the term "colored people" gained racist connotations from its history of being used for discrimination and segregation - and avoiding it for that reason is the primary principle at play. There's also the secondary/less universal principle of preferring "person-first language".
One of the strongest impressions I had were that there were TK-count principle topics in the story:
- The psychological impacts of an ever-increasing rate of change and information flow. Largely a dark view of the future, and one that's borne out pretty well.
- Specific technological inventions or trends. Most of these have massively under-performed, with the obvious exception of information technologies, though how that's ultimately manifested is also strongly different from what was foreseen / predicted.
- Social changes. Many of these read as laughably trite ... until I realised how absolutely profound those changes had been. The world of 1970 and of 2020 are remarkably different in gender roles, acceptance of nontraditional sexual orientations, race relations, even relationships of the young and old. I'm not saying "perfect" or "better" or "worse", or even that FS is an especially good treatment of the topic, only that the situation is different. Moreso than the other categories, the book marks a boundary of sorts between and old and new world. We live in the new world, and the old one is all but unrecognisable.
(Those in their 70s or older may well have a more visceral feel of this as they'd lived through that change as adults, though they're rapidly dying out.)