Sorry I wasn't operating on the premise that you suggested

straight or bisexual women were mainly attracted to male genitalia

I was going on what the OP said, and just trying to amplify - and complicate - your comment that

Sexual orientation is based on sex. Genitals are a part on the attraction, but they are not the only thing that matters.

BTW, I'm not basing my comments solely on my own experience, but on work that's been done over many decades - by sex educators (such as Mary Calderone, founder of SEICUS), journalists, researchers like Shere Hite, sexologists, and what women revealed in the consciousness-raising groups of yore. All of which suggest that, speaking generally, males (in Western countries) overall are distinctly more genitally-focused in their sexual attraction than females; males - again generally speaking - have a more favorable view of the aesthetic appeal their own genitals than females have of theirs; and heterosexual males have a more favorable view of the genitals of both sexes than heterosexual females do.

One of the reasons for the difference is obvious: males can easily see their own genitals and they tend to marvel at them and their capabilites long before they come of age sexually. From the time they are toilet trained, males see and hold their dicks every time they pee. Whereas the way female anatomy is arranged, our own genitals remain hidden from our own view. Boys and men can get a good view of their own genitals just by looking down, but girls and women need a mirror or camera to get a corresponding view of ours.

As an example, men tend to have pet names for their genitals, particularly their penises, to speak of them as wondrous entities, and to use terminology in everyday convos meant to constantly draw attention to their dicks and balls. "John Thomas" in Lady Chatterly's Lover was not a one-off. But women generally do not have pet names for our genitals, nor do girls and women customarily go around bragging about the size of our clits or the lengths and strength of our orgasms. There are no female equivalents to such everyday expressions as "suck my dick," "big swinging dick," "you've got some balls," and "pissing contest." The only equivalent between the sexes in this regard is when references to genitals are meant to be negative, as in calling someone a dick or a cxnt as an insult.

Editing to add: when we talk about sexual attraction, particularly today, we are often talking mainly or largely about visual attraction. So we should keep in mind that for most of human history since the time humans first started wearing clothes, a lot of ordinary people didn't usually see the genitals of adults of the opposite sex very often or at all, not even in pictures. In cultures and eras when it was customary to have sex mainly in the dark, under the covers, or furtively in a dark alley whilst still fully clothed, it's probably likely that many girls and women never saw the genitals of the males they had sex with. And depending on when they were born and in what cultures, many women through history were raised to be so prudish and passive about (hetero)sex that they never touched a penis with their hands or mouths.

Prior to the invention of modern methods of image replication, and of course of technologies of imagery like photography, most people saw very little in the way of pictures too.