salvation is a topic fraught with misinterpretation, very likely due to the use of transactional language. The concept of "debts" and "repayment" was extremely important to people living at that time, and universally understood. For that reason, the topic of salvation in the bible relied heavily on the use of "transactional" language, which was making an analogy between a very obtuse and cosmic event, and something very concrete and earthly (money and debt) that anyone would understand. I would encourage you not to take the transactional language literally, lest you miss the basic point.
Salvation is not about you having a cosmic checking account that needs to be balanced. God created the universe and he doesn't need to invent some convoluted way for you to "repay" a debt that he himself knew you would accumulate.
He died for our sins. Meaning, we are all broken and disconnected from God (thats what sin is), he sent Jesus to Earth to teach and guide us, and show us the way back to him, which ultimately, meant he had to die. That's really it. God's own son, and we killed him. But God knew that it would happen, in fact relied on it. Because to finish the story, he had to bring Jesus back from death, to show us that yes, indeed, he will finish your story too. When you die, he is going to bring you back to life!