To assert that 'mankind' isn't male-centric because 'no one perceives it that way' is to ignore the very evidence that proves otherwise—many people do perceive it as male centric, (spend three seconds googling it ffs) this claim rests on a deeply unfounded generalisation. Furthermore, the suggestion that the introduction of 'humankind' retroactively imposes a male-centric view on 'mankind' is a form of historical revisionism. It assumes that our understanding and language cannot evolve without distorting past usage, which is plainly absurd. Language, much like our society, is in constant flux, and to deny this is to remain willfully ignorant of the dynamics that shape our communication and thought.
ill say good day to you now, as you are clearly either a misogynist or an idiot (likely a combination of the two).
To assert that 'nobody is offended by the terminology' is to commit the fallacy of argumentum ad populum, erroneously believing that majority opinion dictates truth. It's a convenient but very lazy dismissal that ignores the voices of those who do feel excluded by such language.
The suggestion that discussing these issues requires more 'real' interaction is a classic straw man argument. It sidesteps the substance of the debate in favour of a cheap ad hominem attack. It's a spinlessly weak attempt to undermine a valid discussion about how language evolves and impacts inclusivity.