Fun fact: There are actually not just 2 biological sexes. There are plenty of people with other chromosomal make-up that are healthy, living humans.
https://www.scientificamerican.com/article/sex-redefined-the-idea-of-2-sexes-is-overly-simplistic1/
I agree here, I can't read the article without signing up but there are examples in nature of animals reproducing when there is a single animal, I think there are examples where animals have reproduced when it should not possible (which is probably based on or current understanding), do some creatures have the ability to reproduce on their own and have adapted so they can do this.
We are starting to discover what has been there all along, but may have not been looking for it, or looked for other explanations until we decide to reexamine something to gain a better understanding, nature adapts as does science.
Given plants have both male and female parts, I guess we can't put a plant in a signle male / female box as it is too black and white. I don't think plants can self fertilize, which is why insects are important, which of course humans being the top of the intelligence pile (sarcasm) are just destroying them when we know full well why insects are important and essential
I am happy to be corrected on some of this, as I am not a biologist.
