I was watching her NIN races over the weekend. What stood out to me (besides her record-breaking times) is that she looked the part. The stride/form was near perfect. She wore the attire that professional track runners wear (no baggy shorts, rag-tag singlets, hair juggling all over the place). Then you compare that with the other runners in that race (mostly from the northeast), they looked like they just discovered running.
If you dig back into Jane's history, her dad has documented her rise with youtube videos. She has been systematically trained by her dad from young age. No stone unturned. She has a person who specifically coaches her on form. After one of her outdoor track races (where she, again, broke a Utah record), you can see in the youtube video she is immediately getting feedback on her form by her form/drills coach.
There is meticulous detail and the results are showing. Her sister, 7th grader, is close to breaking 5 minutes. But she also has been training for years. Much liker her older sister in middle school, she races predominantly against highschoolers.
Starting early and specializing makes a difference and bucks the normal advice of "let the kids have fun and don't train them until highschool" and "have the kids do a bunch of differnt sports" advice. Jane had already 4+ years of specific training and racing before even hitting 9th grade. She didn't just magically pop up out of nowhere. It was deliberate practice.
And she's enjoying it.