@SecretSlaveClass
I would say you are right on target.
Of course you do have to consider that you are leaning heavily on concepts introduced via the New Testsment. A belief in the devil and demons are post-Tanakh (after the Hebrew Bible was composed), and their connection with illness appears to have come from Hellenistic influences.
There is also well-established exegetical theory that suggests New Testament references to "demons" in connection with health challenges may be partially idiomatic. It appears that sometime after the return from Babylon that a popular view among Jews of health problems drew connections from an attempt to explain them, either connecting them to sin, ceremonial uncleanness, or activity of demonic forces which was new to the scene. Stories like those found in the book of Tobit (which connects a demon to all types of problems) actually became popular in Jewish society. The New Testament message seems to not merely explain a power of Jesus over these types of "demons" but might suggest an exposure of this type of thinking as faulty.
In the end, there was no attempt by any Bible writers to employ a scientific explanation to lessons which were meant to be used for religious catechesis or designed to fit liturgical needs.