Yes. Like a snowball rolling down a hill gets bigger and bigger all their sins were just rolled ahead year by year getting bigger and bigger 'sin ball'. It took the blood of Christ to take away ALL their sins. If the blood of animals could take away sin then there would be no need for Christ to shed His blood.
The verse does not mean God overlooked sin, God's perfect holy just nature does not allow Him to overlook sin.
The OT was a much harder law to live under, Paul referred to it as a yoke of bondage. Again, they did not have the blood of Christ to take away their sins. Hence God was more longsuffering of sins committed under the OT law in view of the coming of Christ.
But it is not this way anymore since Christ came to earth " And the times of this ignorance God winked at; but now commandeth all men every where to repent:" Acts 17:30. God winked at the 'times' not at the ignorance itself. Ignorance is not an excuse for the Gentiles were without excuse (Romans 1:20) in their ignorance. God allowed the Gentiles to walk in their ignorance not bringing immediate judgment upon them when they sinned (Acts 14:16).
If God just overlooked sin there would be no need then for God to call all men to repentance. But again, God was longsuffering not bringing fast judgment their sins deserved, yet they are held accountable presently.
One commentator explains it this way " One object of the death of Christ was to remove the misconceptions that might be caused by the apparent condoning of sins committed in times anterior to the Christian revelation. A special word is used to indicate that those sins were not wiped away and dismissed altogether, but rather "passed over" or "overlooked." This was due to the forbearance of God, who, as it were, suspended the execution of his vengeance. Now the apostle shows by the death of Christ that justice that had apparently slept was vindicated." Ellicott. (my emp)
Again, God did not ignore their sins but just suspended judgement against their sins.