This fundamentally fails to recognize God Himself. He isn't dead to His Body. He chooses who will specific spiritual gifts. Even a conclave of Bishops lacks the power to give something they do not possess.
If they choose to select a particular person to lead their denomination, they have that authority, but it is only a worldly authority and not Divinely instituted. Within that constraint, there is nothing wrong with the last Pope resigning.
It further manifests the RCC isn't a Divinely established institution, but simply another denomination of believers who have formed a worldly institution.
The Body of Christ still has many different members and as a whole they form His Bride.
You get all that from a Baptist observing the Catholic Pope is chosen by Catholics?
wrong again!!! The Catholic Church existed for one thousand six hundred years before there was a "denomination" to recon with...