therearetwogenders

Not necessarily black and white. That statement can just as easily be taken to mean all were created by him regardless of whether they're male or female; which is an egalitarian take not well-liked in Christianity these days, but a valid understanding nonetheless. Notice how it's also referring to humans overall and not only the 1-2 who existed at first. If you believe this can be reconciled with the second version of the creation, that it speaks of male and female humans in the plural cannot be taken to mean that many were created right then and there, only later. So why would the rules be any different for gender?

Another note: the two creation stories are not compatible and this one is clearly a later addition attempting to harmonize with Babylonian traditions acquired during the exile, and promote the Sabbath. It has no other purpose. It does not teach anything valuable or contain any deeper meaning like the rest of the book. The same statement is repeated in chapter 5, but anyone looking at the full context can easily tell it's a gloss. This is a genealogy book, which understands Adam to be the first human's name, whereas in that gloss it's merely a term for mankind in general, which is also the case in the first creation story. The first creation story and this gloss do not line up with the rest of Genesis. The whole book has its problems: one of the books copied to form the 5 books of "Moses" is in fact the gruesome forgery called out in Jeremiah 7-8, which constantly demands animal sacrifices and prescribes deaths by burning. Sacrifices and Sabbaths and holidays and churches and temples are one of the first criticisms in Isaiah as well. And if you look at the Great Isaiah Scroll and see just how much it was edited within the next few hundred years, no doubt the original stated this even stronger. This scroll is also missing several blatantly anti-Christian statements, such as "Don't forgive them". Now it makes sense why the new testament contradicts the old so much, but those in power don't want you to have understanding.