This answer is not specific to JHU and I have no experience there. But it might be useful background. An adjunct position is not a career and it is almost always poorly paid. Those people generally, who live off of such positions typically do "adjunct" for several institutions, have terrible overall teaching loads, and are still poorly paid.
The "ideal" adjunct for universities like JHU is someone who is already employed in industry (say), especially in research there, and who just wants a nighttime activity to keep them engaged a bit with academia and may love teaching. You would probably earn a small stipend per course, but, given that the salary of such a person is usually about double that of the full time faculty, it would probably not change your lifestyle. A retired person from industry who meets the qualifications and who wants to do something interesting, might find it worthwhile.
If you "sort of" fit that description it would be worth applying. If you are desperate for any (any) employment, then my might want to apply.
OTOH, some adjunct positions have union protections that the faculty doesn't have.
Whether it might lead to a permanent position depends on the institution and its rules. I think that at most you would get a small boost in a later application for a tenure-track position provided you fund a way to interact with other faculty. But it isn't really a path to such a position at that institution.
