I grew up calling everyone of any gender "dude". I understand this usage comes from Boston University college slang and it's been around a long time. I once called a woman from Texas dude and she exclaimed, "I am a dudETTE." Lol.
My friends used to call everyone "guys" also, even groups of all women. We liked anything gender neutral, but it did get into a fight with "grammatically correct" whatever that means.