Romans 5:13

13 To be sure, sin was in the world before the law was given, but sin is not charged against anyone’s account where there is no law.

Read Romans 5:13 Using Other Translations

(For until the law sin was in the world: but sin is not imputed when there is no law.
for sin indeed was in the world before the law was given, but sin is not counted where there is no law.
Yes, people sinned even before the law was given. But it was not counted as sin because there was not yet any law to break.