Who was La Llorona? She drowned her kids. Her husband cheated on her, and then she drowned her kids to get back at him. And then he was mad at her, but that didn’t affect her so much as the overwhelming sadness that hit her. Over time she got so sad…
Because she was so sad and realized it was because she couldn’t live without her children, she killed herself too… but her spirit is unhappy so now she comes back and steals other people’s children to make up for losing her own.
How did you come across this folklore: “All of my elders told me; parents, grandparents, uncles used to tell this to all the kids.”
Other information: “This is used as a threat from your elders; IF you’re a bad kid, La Llorona will come and get you… like if you’re misbehaving in the supermarket or make a scene/throw a tantrum outside… or if you don’t listen to your parents, she’ll just come and take you in the middle of the night… We all believed the story… you just innately believe your parents, and don’t think they’re gonna lie to you, you know? And you definitely don’t think your grandma’s gonna lie to you… But just the thought of being taken away from your parents induced the right amount of fear to make it a very real threat.”
Even though it’s not always so believable, particularly outside of childhood or in these specific contexts of being threatened, La Llorona is still real. And the analogous stories (possibly oikotypes) elsewhere in the world show that this kind of theme is important to other groups of people, too, whether it’s used as a threat to make children behave, or to scare newcomers, etc.