They're not mnemonic for any specific usage because they have more than one possible specific usage in the language.
Besides, what kind of sense does '+' make for addition? It's also purely historical.
So you choose 'cell' as your name for a node. OK, that's .. fine.
Now you choose 'car' and 'cdr' for each cell's 'data pointer' and 'next-cell-in-list pointer'. How many 'WTF?s'* do you think you'd get in code review? (except from lispers, I guess)
* obviously it's a rhetorical question, no-one writes or says WTF (out loud) in actual code reviews I hope.
Your names are too verbose.
node->data
node->next
Zero "WTF"s
The point is they are 'wrong' in every context. For LISt Processing, they should probably default to something to do with lists.
And caaar et al are a fine example of why I completely skipped common lisp in favour of newer lisp-likes. Perhaps it happens to all languages eventually, people add a convenience here, an shortcut there, and a doodad here, and before long you have an impenetrable thicket.
And these things seem convenient, but they are a huge extra cognitive load, and impose a further learning cost even to practicing experts who have to keep up with the latest doodads.