There are not two different creation events.
Gen one says God created Adam - meaning a human being - (not a male) - which Gen 1:27 says was male and female in one.
We have ancient Hebrew texts with this exact story.
Gen 1:27 So God created ADAM/human being in his
own image, in the image of God created he him;
male and female created he.
The next story in Gen 2 is just an extension of the first - explaining how the Adam/human that was both male and female, - became separated so they could reproduce.
As for that X and Y chromosome - female is the default, - not male.
That Y is some kind of corruption/mutation.
"The Y chromosome is responsible for determining male gender in mammals. The Y chromosome contains the SRY gene, which is necessary for the development of the testes in males. Without this gene, no testes would develop
and a fetus would grow into a female."
"The two sex chromosomes in humans are thought to have evolved from a pair of autosomes due to the presence of an allelic variation on one of the chromosomes in an ancestral mammal. The chromosome with the alteration became known of as the Y chromosome and the remaining autosome became the X chromosome. The Y chromosome slowly developed or acquired genes that were advantageous to males but not to females.
The Y chromosome spans approximately 58 million base pairs, contains 86 genes, and represents around 2% of the total DNA in a human male." http://www.news-medical.net/health/Y-Chromosome-Evolution.aspx
"The Y chromosome is considerably smaller than the X chromosome and has a much
lower density of genes. In fact, the Y has often been called a "genetic junkyard." But there are a few rubies among the rubbish of that genetic junkyard: the Y chromosome contains the genes are essential for male fertility and other male characteristics."
The facts are that if there was no X in you - you would not exist. The greater density of genes that we NEED - are on the X.
"Why does the Y chromosome have so few functional genes? Evolutionary biologists are still debating the details but they agree that the lack of recombination explains the paucity of functional genes on the Y. Unlike the twenty-two pairs of autosomes, there is no recombination between the X and most of the Y chromosome.
Genes on the part of the Y chromosome that does not recombine will be passed from father to son, down a paternal lineage, and will never be present in females. The lack of recombination weakens the effectiveness of natural selection to weed out bad variants and select for good ones. Over many millions of years mutations and random genetic drift erode the Y chromosome, turning it into a genetic junkyard.
In contrast, genes on the X are present in both males and females; X chromosomes, like autosomes, recombine in production of female gametes." https://www.learner.org/courses/biology/textbook/gender/gender_2.html
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