The hot tl;dr of this that is going to get you a lot of angry boys sending you incoherent diatribes is that we haven't decided as a species that we will stop sexualizing youth.

Yes there are biological imperatives for the sexually aggressive sex to seek out mates that are young, healthy and capable of producing offspring before they become too old to reproduce. That's all a thing that's real, but it's as far distant in our past as most other ancient instincts that we've put to rest. We just keep this one alive because we want it to continue broadly. The whole notion of older men predating and sexualizing youthful appearances or "innocence" as standards of femininity is absolutely something that if we all decided together was no longer acceptable, it would end tomorrow. (Or realistically in one generation.) This is not a more natural part of us than anything else we choose to follow or not, because we are well above using any natural response system as an excuse to allow dangerous social norms to continue.

The reason I say this is because there are a lot of men who will secretly or overtly hold the position that since we have biological urges, then it must be natural and acceptable. Meanwhile, ya'll fuckers completely ignore the thousand other biological drives and standards that we've abolished because they're unproductive, hurt people or just have gone out of style.

For example: body odor. Do you really think we were using soap and perfume when we were packed together in huts and caves for the last thousand millennia? You are genetically identical to the people who used to bury their faces in each other's armpits to identify each other in the dark, but the thought makes you gag now because you were socialized to feel repulsion at this. (Fetishes aside.) We can socialize ourselves to believe and internalize almost anything, we are far, far beyond the forces of natural selection and are now choosing our evolutionary path. Wouldn't it be nice if we chose good paths that respected others and protected children.