I used to see this parable the way you do now. In fact I ruined my relationship with my sister many years ago because of my misunderstanding of this parable.
Christ was talking about the law under the Old Covenant. Under the law forgiveness was possible but sin was only covered temporally. There was no change of heart provided for those who lived under this Covenant.
All the people under the Old Covenant did not have Christ living inside of them. They did not have a new heart. They did not have the fullness of the Holy Spirit. They were NOT born again. They really were not Christians.
This parable has nothing to do with Eternal Security in any way whatsoever.
Under the New Covenant, Christ removed all of our sins. They are now totally gone not just covered. We were given a new Heart and a New Spirit. We now have Christ's Life inside of us. Do not forget that the problem of mankind's sinful corruption was so bad and thorough that even God, Himself could not repair us. There was nothing God could do with that sinful nature, no touching up, no revising, no improving it and no adding to it could ever make it acceptable in His sight. Our sinful nature was entirely hostile to him and we were His actual enemy. We were so corrupt, so wicked and evil that the only thing God could to do with our sinful nature was to crucify it with Christ. The only possible cure for your old life was death.
The Good News is that God has already provided the solution for us in Christ. When you were born again you experienced the reality of what God in Christ had already accomplished before the world was created. We were crucified with Christ and you were buried with Him. Your old sinful nature died and you received God's Divine Nature to replace it. The only solution was to have us crucified with Christ and then He gives us His LIFE. So we died, and we became a New Creation. God made us righteous, holy, clean, purified, and justified. We have no need to become a better person, because God has already made us into a new person.
If you are a Christian then you are actually enjoying your perfect union with Him. He made you a NEW CREATION. You were made 100% righteous and perfect. You are one with Holy Spirit or the Spirit of Christ. You no longer experience that old life in Adam. You now hove a new pure heart and God's very Divine Nature. You have received His all-sufficient Life in exchange for your old corrupt self. Now the Christian life isn't yours to live.
God does not depend on you to live His Life for Him. He knows that it impossible for you to live His Life, so you experienced His life when you were born again. You do not live for Him - He lives for you. Now you can fully depend on God's Life rather than depending on what you do or do not do. You no longer need to make promises that you can never keep or try to dedicate and rededicate your life to Him. You now have Christ living His Life through you. You no longer have to try to make the Christian life work through your own efforts and resources. It is only made possible by your union with Christ in His death, burial and resurrection.
This is all God's gift to us. We can never deserve it or earn it. We seem to take it very lightly that Paul said, "I have been crucified with Christ" and "I died." But those are powerful statements! So, what died? What was crucified with Christ? Our bodies obviously didn't die. Our souls didn't die, we can still think and feel and we still have make choices. So what died was our spirit that had been born in Adam - our sinful nature. When we were born again, we still had these old bodies and souls, but we now experience that fact that our sinful nature was killed - dead, gone, crucified - forever - and we were raised to life with the righteous nature of Christ.
You have died and were created anew. This is referring to the very essence and core of who we really are. This is the reality of who we really are in our spirits. God didn't take the "old us" and change us into a "better" or "improved" us. Rather, we died and we were re-created as a brand New Creation. We haven't been revived. We've been regenerated and re-created completely! In other words, God didn't take the old us and pump some life into it. Rather, we died and God made us into something completely new - a New Creation. Our old life wasn't changed. It was exchanged with a real life - the very life of Jesus!
Eph. 4:32, "And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you."
Now we are able and can freely forgive because of our union in HIM.