“Why do we think sex matters more than the others?”
In general, because our species dies out of you don’t pair properly. You can pair a colorblind person with a nearsighted person and if the organs don’t match up, no reproduction.
Throw in that our society is set up in a fucked up way that we need to increase the population at all times otherwise we won’t be able to care for the elderly before us (social security, medical care… Whatever it may be) reproduction matters a lot to our society.
All of those ways include a male and a female as far as I know? More steps are added, like moving the sperm or egg, but in the end it is sperm and egg. Gender is what you are describing as socially constructed as per textbook definition. Infertility occurs, if you want to say they aren’t male or female, or say they don’t have a sex until they are sexually mature and that ends when they are no longer able to reproduce there are other names, but I think that is just overcomplicating something that was painted with broad strokes. Is it “moral/ethical/correct/right” that’s for the beholder, but if your battle is just about the terminology of how to classify someone’s anatomy, I’m for hoping it goes well. The more people learn, and the less ignorance about how reproduction works should make the world a better place long term I hope. Out of curiosity do you mind me asking what part of the world you live in? It’s been nice discussing this, always good to hear what others are thinking/learning.