Female erotic plasticity

I came across a study (https://psycnet.apa.org/record/2007-17941-013) where men and women were shown sexual activities of men, women, and chimpanzees, and their arousal was measured. Men responded more strongly to the gender of the actor (I.e. straight men were aroused by videos of women, gay men by videos of men) but women's arousal was not heavily influenced by the gender of the actor. Also, women were aroused by the video of chimpanzee intercourse, whereas men were not.

In another study (https://www.nature.com/articles/s41598-017-18372-0), men and women's brain activity was scanned while they were viewing erotic stimuli. Men's arousal was consistent with their sexuality (straight men were aroused by women, gay men were aroused by men) but "straight" and bisexual women showed indifference (they were aroused by both men and women). Lesbian women, however, were only aroused by other women.

Can anyone explain this? The common explanation for female erotic plasticity is that women's sexuality is more socially influenced by men, but that still leaves some important questions open:

1. Why would female sexuality be more influenced by society?
2. How has social conditioning led to women being turned on by chimpanzees having sex?
3. Does this prove that all women really are either bisexual or lesbian?

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BIG EDIT AHEAD, MAYBE IMPORTANT INFO AT END:

After digging into this a bit more, there seems to be pretty mixed data and these two studies should probably be taken with a very large grain of salt. The researcher behind the first study (genital response) did a lecture on it and she seems to believe the preparation theory (genital arousal to avoid injury during sexual assault) likely explains the general genital arousal women experience towards any sexual stimuli. She used the women's genital arousal to chimpanzee sex (and other examples of arousal to nonpreferred sexual activities) to explain this. She also talks about other research where women read erotica instead of watch porn, and the general genital arousal goes away and they respond much more strongly to erotica that is of their preferred sexual orientation, while showing no arousal towards subjects like chimpanzees fucking or sexual assault. She also talks about interviewing the straight women who were aroused by images/videos of other women, and she says that they could notice signs of physical arousal but felt zero real desire for the women in the porn.

As for the second study, if you actually look at the raw data, women do show gender specific arousal, they just seem to have subdued arousal to all of the erotic stimuli in general. I then found a bunch of other studies that show men having similarly bisexual tendencies to the women in this study (the men being attracted to some degree by male porn regardless of their reported sexual orientation) and heterosexual women showing much greater neural responses to heterosexual porn vs bi or lesbian porn. Plus many studies show men showing greater responses to visual stimuli, while women show greater responses to other forms of sexual stimuli (stories, sounds, etc.) And they also show women being more likely to imagine themselves as the women in the porn, which may also contribute to the general arousal.

The way I interpret this is, women evolved to experience some degree of genital arousal to any sexual stimuli in case they get raped, and this function requires at least some brain activity (hence the activity on the brain scans). They also don't seem to really care for the highly visual stuff, so they experienced more of a baseline physical arousal (brain response + genital response) but not much beyond that, whereas men responded more favorably. Lesbians were the only women who responded to the visual stuff, and they responded unfavorably to men, whereas bi and straight women just didn't care either way. But when you give women their preferred stimuli, they respond much more like men with more clearly defined heterosexuality, bisexuality, and homosexuality. So no, all women are not bi. But they have the baseline physiology to make bisexuality more accessible, whereas a man could be romantically attracted to another man but physically incapable of having sex with him because he can't be physically aroused. In the same way, men are more likely to be strictly homosexual than women because they may only experience physical arousal to other men, while homosexual women may experience at least some arousal to women and men. This may also explain why men tend to seem more interested in sex than women, because women may have evolved to largely associate sex with being raped.