There are gay women that say they are "into penises, but not into men, so trans women work"

Evidently not gay then.

gay men that say they are "into vaginas, but not into women, so trans men work".

Another example of someone not being gay. Your argument builds on the opinion of supposed gay people yet you don't mention anyone who is actually gay, just people who are attracted to the opposite sex.

What's wrong with "women can have penises, testes, sperm, etc,

Everything.

Why would the words "man" and "woman", "male" and "female" be reduced to sex organs and gametes?

They have never been reduced to that, the very definition you criticize clearly states that men and women are adult humans of a certain sex, aka also adult and human, not just floating sex organs, and the human factor is very encompassing, the exact opposite of reductive. Being adult and human is just not the distinguishing factor between between men and women, as both are adult and human. The distinguishing factor being reduced to sex organs and gametes is good thing though from an anti-reductivness perspective, had we declared the distinguishing factor to be anything else than that then that would have truly reduced men and women to a set of stereotypes. Imagine if we had declared the very encompassing human trait to be the distinguishing factor, then either men or woman would have to be seen as inhuman for that to be the distinction between them.