Thanks for sharing Mike. Just so you know this OP came from Got Questions as a conversation starter. I'm not saying personally that I'm in agreement with their points. I'm a former calvinist of 40 years that left it a couple of years ago so there are many things that Reformers believed that I no longer believe myself.
You might be in the no mans land I was in, when reformer doctrines did not make sense, and all the division proved to me sola scriptura was not enough by itself. Yet at the time much of catholicism did not make sense to me either!
The answer for me in part was to read the testimonies of many who returned to the catholic church in (such as) patrick madrids reason to believe books. I discovered many in the protestant and evangelical world shared many of my concerns about staying or going from it. Newmans essay on the development of christian doctrine is useful as a warts and all none rose tinted view of the faults of catholicism but he studies the development of ideas and how disputes ended up resolved.
One aspect of the background of protestantism that escapes much attention is the era after aquinas.
Aquinas had the classical view of scientia - the balance between faith and reason both as sources of truth.
Shortly after aquinas the combination of marsilius , occam and machievelli changed the way the world viewed faith and reason.
Faith was deemed to have no reason, and reason became seen as the dominant truth over faith.
That paved the way to the enlightenment later.
Luther was a stated follower of occam.
It matters because increasingly faith without reason led to a God perceived to act without reason.
So the God of the creed and Lords prayer was a father with a covenant not master slave relationship who wanted all his children to succeed and come to Him as a father of a family does.
Increasing the detachment from reason led to perception of God too acting as master without reason becoming the Calvinist view of double predestination, the elect elect without reason, tough luck if you are not one of the elect. That Gods sovereignty and ability to choose arbitrarily trumped his father hood.
That is a long way from the God of a father children covenant, who is willing all to succeed unless you choose not to be part of His family.
Later the enlightment tried to rid itself of all faith. Now leading to the scientism of today.
So protestantism was also founded on a changing view of faith and reason.