@lindaB1978, I presume when 'Max' was born the midwife told you what sex your child was?
You say that 'Max' identifies as a 'demi-boy' and this confuses you. I'm pretty sure it confuses 'Max' too. How old is Max? A teen I imagine. Why would you as a woman, a mother, with many years more experience of the world than Max, accept this odd classification that your child has chosen for themselves?
Time itself always moves forwards, but ideologies don't. The Renaissance and The Enlightenment existed because there were ages of bleak adherence to bonkers ideologies before them.
Don't blindly assume that human progression is linear.
Peaks and troughs, ages of stupidity, social contagion of crazy ideas is as old as humanity. Times are and always will be moving but don't think they are always moving to betterment.
It behoves you to be aware, not to knowhow. Ask why, question, accept nothing as cant.