First, everybody should take note of the fact that you still haven't provided a source showing that trans women have any sort of across-the-board competitive advantage over cis women in sport. I can only presume that's because you don't have any. Pathetic. Moving on.

Claiming that the fact you're arguing from a "basic" understanding is somehow a point in your favour is some pigeon-shitting-on-the-chessboard-and-claiming-victory type shit, and you should feel embarrassed.

Sure, you personally are allowed to use a model of sex as determined by the presence or absence of a Y chromosome, but such a model is overly simplistic, and to act as though that's the only correct model that either society or science broadly operates on is completely disconnected from reality.
This should be painfully obvious to everybody, given that people have been determining sex since long before the discovery of DNA, nevermind sex chromosomes. Likewise, medical staff determine the sex of babies not by running DNA tests, but by visually examining the genitals, ie a primary sex characteristic.

But furthermore, a Y-chromosome-as-sole-determinant-of-sex model is flawed for other reasons, too. For one thing, it's not the Y chromosome itself that causes male sex development, it's a specific gene that just usually happens to exist on it: the SRY gene. Someone can have a Y chromosome, but lacking the SRY gene will develop a female phenotype. Conversely, it's also possible for the SRY gene to attach itself to an X chromosome and cause someone lacking a Y chromosome to nevertheless follow a male pattern of sex development.
Now get this through your skull: the SRY gene doesn't actually do a whole lot, either—it mostly just instructs the gonads to develop into testes rather than ovaries, and it's the—you're not gonna believe this—sex hormones which the gonads go on to produce that cause the body to develop pretty much every primary and secondary sex characteristic down the line—barring insensitivities to them, of course, and it is in the actual materially observable sex characteristics, primary and secondary alike, that people are most likely to realise differences in sex, rather than in some chromosome we don't know is there or not until it's specifically tested for….
And gonads can be removed. Primary sex characteristics can be surgically altered. Exogenous sex hormones can become dominant in a person's endocrine system and can cause the development of new secondary sex characteristics.

So relying on just the Y chromosome as a measure of sex comes across as really arbitrary and not functionally useful, given that it doesn't really do a whole lot. In fact, the only reason I can come up with as to why one might hyperfocus on the Y chromosome would be to be shitty to trans and intersex peolpe 🤷‍♀️
Also, given that not all red blood cells contain DNA, you're wrong again—it's also not written into every cell of a person's body 🤓👆
And finally, it's a blatant example of hypocrisy for you to say I'm equating tits and vocal tone to the essence of human sex (which is itself a wild misrepresentation of my argument) when you yourself did the exact same thing earlier with height, wingspan and lung capacity, which are all also secondary sex characteristics 🤣 make it make sense 🤣🤣

You're clearly being intellectually dishonest here, because you know you haven't got a leg to stand on. Dickhead.