Adam, the first man, knew of God, and directly disobeyed him leading to humanities fall. We have the promise of a savior since Adam.
Since Adam ate the fruit, humanity knew the difference between GOOD and EVIL, and God can judge on that basis, or on the basis of a hope in a future savior.
Since Moses, humanity had the 10 commandments. Therefore, God can judge based on that, or in the hope of a future savior.
Since Jesus, we’ve had the fulfillment of the bible, and God can forgive transgressions of the Law through human repentance.
So, ignoring that the vast majority of humanity has heard of Christ, the question is “What happens to humans who have never heard of Christ?” I believe God will judge them based on their knowledge of Good and Evil. This question also calls into question God’s sovereignty, if God wants someone to know Christ, they will!