Residency programs receive at least hundreds of applications for a handful of spots, and interview a small percentage of these. I promise you they are not interviewing candidates they are not seriously considering. Yes, there will be candidates that are weaker/stronger based on the paper application alone (including grades, evals, LORs, test scores, school might provide a boost but in my experience does not take away). But going to the worst school in the US will not keep an otherwise stellar candidate out of a residency program once they have been interviewed. A bad interview will. This is especially true if you received numerous interviews, as you claim you did, and still fell low on your list.