Earlier quoted context omitted.
The grammatical gender of nouns is mostly arbitrary. A famous example is "key", which is feminine in Italian and Spanish but masculine in German. This is also the case in Latin with its neuter. My Latin is very rusty, but IIRC from high school, there are a lot of nouns that refer to "neuter" things, but are actually masculine or feminine, for example "vis" (= strength) is feminine.
well noun gender does seem disconnected from the nature of the thing only in modern languages, IMO. because of how each word evolved. in antique languages, grammatical gender is closely tied to the word's morphology, especially to the word's ending in Latin. in essence there is not really gender in languages, just some group of nouns which behaves very grammatically similarly. they just happened to be suspiciously co…
It doesn't say that "Schlüssel" has a Latin origin (see also https://en.wiktionary.org/wiki/Schl%C3%BCssel for an etymology). It says that some terms related to Latin "clavis" have corresponding German terms formed by somewhat analogous derivation from "Schlüssel". Most prominently "Schlüsselbein", literally "key bone", from "clavicula" (clavicle).