she is a 13 year old little girl. The song was written by an adult, and the music made by adults. She was just put to sing it. She has a decent voice for a kid, and she seems like a sweet girl. I think people are way to mean towards a child who is just having fun singing a song.
It's impressive, a cute little girl made a catchy little song. So what if it's not professional quality?
And even if it isn't professional quality have you seen what passes for professional quality music sometimes? Half the singers on the radio don't sing and their voices are computer enhanced.
Leave the kid alone.