People with different blood types don't function differently. People with blood type O don't have greater muscle mass than people with blood type A.

Sperm and eggs are required for making a new human. There are no speggs. Two sperm or two eggs cannot make a new human. Sometimes there are people who can't produce gametes. Intersex variations are disorders in the sense that their bodies don't function as they should. That doesn't mean they can't live long happy lives with minimal impact, just as people with heart defects or extra fingers can. Why does having a birth defect of your genitals somehow make you a new kind of human? Are people with an extra finger a new species? Why do we treat congenial defects of the reproductive system differently than any other kind of medical issue? There are people who are born with only 3 heart chambers, does that make them half lizard? There are people born with a small tail, are they more primitive that people who aren't? Occasionally a human will be born with a small gill slit, are they part fish? The answer to all of these is obviously no, they are human. Just as women with enlarged clitoris (which looks like a penis, but isn't one) are still women. Men with excessive breast tissue are still men. The vast majority of intersex people have repeatedly stated that they don't like being part of the gender debate and that they don't like being called a 'third sex' or something else othering.

Saying 'male" and "female" is so much simpler than "people whose bodies were developed around the potential to produce eggs".