Let me put it to you this way.
Nick Symmonds was 91st at 2005 cross country nationals. At that time he was a "soon to be" 3:40 1500 runner within the year such as you are a self-appointed 4:15 runner.
In the 2006 swampfest Will Leer was 7th. Later that year during the track season he would run his own 3:40.
4:15 for a FULL mile would not even qualify you for the indoor mile last year nor the year before. I assume you speak of the 1600 since you are in HS and that would probably convert to a 4:17 full indoor mile. However since the nationals provisional time is 4:16 your name would not even appear on the performance list, much less be in the top 18 selected to race at nationals, much less be top 5 in the mile race whose field is a fraction of the size of the national cross country race.
So you see there are people out there that are athletically far superior to the time you have never run and yet they still failed to claim top 5 at the D3 national cross country meet. I am teammates to one of the freshmen named previously who actually ran your projected time and it is true he did not make the top 7. Don't kid yourself, the top tier D3 guys can run their asses off too.