This is the single, most salient point in favor of sola scriptura. Imagine this same hubris, but spanning century upon century, formed of whole cloth, by the fiat of human councils, by declaration of their own infallibility, bound in compendiums and given the same weight of authority as the Holy Oracles of the Lord, God Almighty.
Given the bare fact that error must exist, as evidenced in the normal course of human judgment, how can one correct or remove such human error if it is given the same weight as the Divine? It makes no sense at all.
The very first charge of the Church must be to preserve The Message. There can be no higher authority than that we know to be the Holy Word of God. It must be the final arbiter, as it is the only standard that we know to be true.
We do have a propensity for sin...Babies are not born righteous...Babies have no desire to be obedient to the will of God...Babies are born with a sinful nature...A propensity to sin...
I am willing to cede the point. 'Default' was too harsh a word. But whatever we are now, must, by the nature of the curse, be worse than the condition of Adam, who, without the curse, still had the ability to sin, and arguably, the inclination to do so as well.
If God thought it was necessary, He would have told us...And maybe He did tell us if we spend enough time in the scripture to find out...
That is my point in a nutshell. That which we do not know, we do not know, and in such a condition, we would do well to believe in the Word of God.
I think it's amazing that you equate your personal interpretation of scripture with God.
The result has been thousands of Protestant denominations; each little Protestant pope setting up their interpretation of Scripture as the one that is correct.