But still, if I am morally incapable to be "perfect as my Heavenly Father is perfect", should I still be responsible when I can't be perfect physically, emotionally, mentally, spiritually, etc? I think the answer is, "yes I am responsible", but I'm not 100% sure how to prove it
Galatians 5:1 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage. Sin was, as you said, inevitable. Only Jesus lived a perfect life. Now that we are in Christ, who still lives that perfect life in us, we are free. Yes, we deal with the frailty of the flesh, but our identity is now in Him. As we learn to abide in Jesus, more and more fruit we bear, becoming like Him through seeing Him (II COR 3).