Biological sex is part of how our species functions.

Race is how humans have decided to classify each other based on arbitrary phenotypic traits (i.e. skin color, hair type). How people define race has changed over time and across different cultures. While people have had different ideas about gender roles, they have never had any different ideas about sex.

Females produce eggs. Males produce sperm. People who don't produce either still have (or had) the equipment to produce either sperm OR eggs, never both. Its really that simple. How do we determine what sexes are in non-human animals? or even in plants? By seeing which ones produce the eggs. If biological sex isn't real, then why can't I have a rooster lay eggs? If biological sex isn't real, the shouldn't a baby form from any combination of gametes, since they are 'basically the same'? The amount of genes being shared means absolutely nothing. There is in reality, only one single gene that matters, and that is the SRY gene. The SRY gene (located on the Y chromosome) triggers male development and its presence/absence determines what type of gamete an individual makes, and thus their sex.

Gender roles are not sex. Secondary sexual characteristics (i.e. facial hair, larger adam's apple, larger breasts, etc.) are not sex.