Asklemmy

To provide some responses to your extra questions:

I don’t think “female” is offensive.

The frustrating thing about offense is it often relies on people having a different perspective, which sometimes is obvious (especially with terms clearly used as insults) but sometimes is more subtle. I feel that it helps to seek out a properly-explained reason someone is offended, to understand the context rather than just the text.

LGBTQ+ politics is confusing …

It's not even that (those letters stand for things and 'female' isn't one). It's not even feminism either, I've seen "femcel" misandrist groups using 'male' the same way to alienate and objectify. Some other people have already explained, it's a technical biological/medical term that is legitimate, but some people (especially those who don't like women) use it in a context that is dehumanizing and objectifying, by not using adjectives or nouns more casual and specific to people. Context is the big thing with offense and something I think needs to be emphasized.

I understand that the nuance, like most social nuance, my seem silly and a big thing to care about; a woman is literally an adult female person and that isn't in itself an insult, it's a category. But using technical language in a casual context can be interpreted as treating someone like they're an object of study rather than a fellow human, same with referring to people as 'it' (a few people are fine with that for they purpose of explicitly denouncing the concept of gender, but most people would be offended if you referred to them as 'it' instead of (for examples) their name or another gendered pronoun).

I think much of it comes down to how "male/female/intersex" are often used in non-technical language when referring to animals (or flowers or electronic connectors), whereas "boy/girl/kid/man/woman" and others usually refer to humans (although they are regularly used also with pet animals, which people often like to humanize and develop personal bonds). That's why some people are instinctively offended by male/female in a casual non-technical context, like "I find you males interesting" or "It's easy to talk to you guys, but females make me nervous". It's alienating and sexualizing.