I have not noticed much impassioned debate about the non essentials (when both sides agree they are non essentials.)
What would you consider a non essential?
You ask very good questions.
I see a stark contrast between the Old and New Testment - in the Old Testament spells out explicitly how the Jews are to worship, what they do, how to do, when to do ...
The New Testament does not give the details - but high level principles - like the character of the leaders, how we are the treat our neighbor.
Jesus often went back to Genesis - skipping the Jewish covenants and promises and rules, to the Garden of Eden as to original purpose of men and women - caring for God’s creation and principles of marriage. When there was a person in need who was an outcast - publicans, Samaritans, women - He ministered to them.
I see the non-essentials as the specific details not explicitly spelled out that don’t contradict the great principles that are. Therefore, I cannot say Catholics are wrong in the details they worked out. (They worked for 2000 years) Nor other denominations or those not affliated are wrong either as long as they they don’t contradict great principles. Jesus is Lord and we have no other Savior but Him.
I gave it my best shot. But I’m still learning ...