It’s completely context dependent; you’re right that using male/female is appropriate for humans in certain contexts, e.g., medical usage (“Patient, a 47yo female, presented with…”). But it is — for cultural and historical reasons — generally considered inappropriate to refer to our fellow humans that way in conversation.

Re: mutt, fair enough. Bitch/stud are examples of how animal terms, when applied to humans, take on very different meanings. Purebred is afaik not specific to species, but it is wildly inappropriate to refer to people as such.

At the end of the day, the logic behind what is and is not appropriate has history behind it; animal terms have been used extensively to refer to subjugated peoples; it may be scientifically accurate but that doesn’t mean that it’s inoffensive.