Years ago a university chemistry class got a guest lecturer for the day. Afterward the students were asked about the lecturer. They all agreed he was the best chemistry lecturer they'd ever had, bringing the concepts alive for them as never before. They figured he must be some Pulitzer Prize-winning genius.
In fact he was a professional actor who knew nothing about chemistry.
The point wasn't what he knew or didn't know--it was what the students learned when they listened to him.
His area of expertise wasn't chemistry--it was communication.
Likewise what Jackie Evancho knows is the language of music--of tone, of phrasing, of portamento (all those little notes that aren't in the score), of passagio (seamless transitions from chest to head voice), of vibrato.
If you played just the audio of "The summer knows" for someone who'd never heard--or heard of--her, theyd probably say the singer must be a tall, heavyset (to support the big voice) woman in her 30s, who's been around the block a few times.
I've tried this experiment and that's the result I usually get.
It's important to note that Jackie never tries to act a day older than she is. That's not the way in which she's precocious.
As for what she herself understands--of course she knows little about romantic love etc. But she does understand--as do many 12 year olds--love in a more generalized sense, and longing, and loss. Jackie just does more with that than most.
So she's the storyteller, not the story; a conduit for your own life experiences, not hers, connecting those experiences to those that the song she's singing deals with.
Lastly, she's not a "child singer." There are a lot of those. They sound like children. They're cute. They compete with other children.
Jackie is a singer who happens to be a child. From the start she has competed with adult singers for sales of her CDs, DVDs and concerts. She sings in an adult voice. she mostly sings songs other adults sing. Her CDs chart on Billboard Magazine against those of singers like Andrea Bocelli and Josh Groban. And her fans are rarely fans of child singers.
It's hard for critics to categorize Jackie because in a way she's a category of one. There has never been a child in history of recorded music who sounds/sounded like her. Julie Andrews, at Jackie's age, sounded like a child with a beautiful, agile, wide-ranging child's voice. She didn't sound anything like Jackie, who's not as agile and not quite as wide-ranging, but whose tone and texture and vibrato aren't excelled even by highly-trained adult singers.
Some people get there by training, others by sheer talent. Jackie's the latter--living proof that we're not all born the same.