What bios are you talking about? Because no where is she called or emphasized with the term "innocent." And it's certainly not the Remake bios. The Japanese Ultimania bios for her emphasize her being kind but also mischievous and playful. And Nojima has always characterized and described Aerith as playful and
flirty. If anyone is modest, it's Tifa because she's shy, but she clearly isn't that shy given what she wore to her mountain guide job when she thought Cloud was coming. I don't know where anyone is getting this idea that they're trying to make her or Tifa innocent.
The only implications I got from Aerith never thinking about
children is the fact she never pictured herself having a future that far into her life. It's not about being innocent about sex, it's about her not seeing a future where she carries on the Cetra legacy. An unconscious pessimism of her future.
@Phantasia hit the nail on the head as well. There's nothing going around about innocence here, they're very much aware of reality and what they're looking for.