I think this discussion has a significant problem: «modernity» is not defined. In fact, I use this term with a different meaning that the meaning you give it. Let me unify the terminology so we can discuss instead of talking past each other.
A simplified definition of modernity:
Modernity = Technology + the religion of individualism
With «the religion of individualism» (RI, from now on), I mean the religion that derives from the Enlightenment. Its main god is the individual, the will, the self. Freedom and equality are second-level gods and it has many third-level gods: democracy, tolerance, relativism, etc. It has had different sects: classic liberalism, marxism or political correctness (which is its present version).
On the other hand, technology derives from the scientific revolution started by Galileo (which introduced the experimental method in the natural philosophy). This technology produced the industrial revolution and the most prosperous age in the history of mankind.
When I said that «modernity is only secular Protestantism», I meant «the religion of individualism (RI) is only secular Protestantism». Now, you assume that these two elements are impossible to separate. You say that Penicillin would have been unable to be produced and distributed under the socioeconomic circumstances of the Middle Ages. I am not that sure. I don’t see why corporations (https://en.wikipedia.org/wiki/Corporation_(feudal_Europe)) or guild could have not produced medicines if they had had the technology. Could you elaborate more?
In my view, each age has as much sin as can be economically supported. The human instincts are programmed to the environment of evolutionary adaptedness (EEA) https://www.alleydog.com/glossary/definition.php?term=Evolutionary+Adaptedness+%28EEA%29+
So if you let humans follow their wishes (their instincts), they end up reverting to a hunter-gatherer society, which is a disaster in our civilized society (I don’t explain here why this is a disaster because it would be long). IMHO, this is the «original sin» taught by the Church.
What prevents that is that humans cannot follow their wishes because of economic constraints. So when an age is prosperous, humans can follow their wishes more, that is, there is more sin. Of course, history proves once and again that sin is proportional to wealth. Compare the early Rome with the late Rome, our grandfathers’ time with our time and so on. This fact was already known by Roman intellectuals.
Imagine the modern family system practiced in the Middle Ages. Lots of boys without father and women without husband, for example. It would have been impossible. These boys and women would have starved and only the more puritan people would have survived. This is possible today because we have a lot of economic surplus (due to the productivity created by technology). Through taxes, this surplus is devoted to support this modern family system: lots of public services, welfare, help to single-mom families, etc.
As I said, each age has as much sin as can be economically supported. So the cycle of history is:
A poor and puritan age produces wealth.
The wealth allows more sin to be committed.
A wealthy and sinful age produces debt and bankruptcy.
The poverty produces puritanism and the cycle starts again.
As technology produces more and more economic surplus, more and more sin (debauchery) is possible but it needs an ideology to justify it. The Enlightenment (derived from Luther as I said) found a clever way to rationalize this debauchery. The human instincts, which were previously considered as bad («original sin») were considered as good (Rousseau) and were called them «liberty» or «freedom». This rationalized our modern debauchery and is the «religion of individualism».
In short, it would be useful in our discussion to specify what we are referring to: the religion of individualism or the technology. «Modernity» is an ambiguous term.