A lot of people in the world say they are "not worthy" of God's grace or forgiveness. I suppose that is the point. They are not worthy but God wishes to forgive them anyway.
You see God is a God who wishes to forgive. He already knows you are not worthy.
He knows who you are and what you have done and wishes to forgive. You see and meet many people in the bible who do not understand why people are forgiven.
Jonah does not understand why the Ninevehites are forgiven. Why are so many sinners forgiven by Jesus? Surely he should not forgive these terrible people.
You see the point is God forgives who he wishes. And he wishes to forgive all that want forgiveness. He will not turn any away who knock at his door.
There is more grace in God than there is sin in you.