Romans 1..does not save anyone. It let's them know there is a God who they must answer to, hence they are without excuse. Without special revelation ,they perish in Adam. Rom .10:
14 How then shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher?
15 And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!
Paul and the scriptures give no indication of such salvations happening. Missionaries find Idolatry everywhere, as the rest of Romans 1 describes.
We were talking about what sends man to hell who has never heard of Christ, who has no knowledge of Him.
Before Christ came man was saved by looking forward to the coming Christ through the Sacrificial System of the Law. The animal sacrifice was the means for the forgiveness of sins with Christ representing that sacrifice.
Before the Law and all the way back to the Garden of Eden the animal sacrifice had the same meaning. We see in Cain an Abel the animal sacrifice that represented Christ was accepted from Abel, but the vegetable sacrifice was rejected from Cain.
We see several times in the OT where God sent the Hebrews of old who knew and practiced faith in the sacrifice that represented Christ, to those who God knew would believe. Rahab the harlot comes to mind, the Gentile widow woman that God sent Elijah, Naaman the Syrian who God sent to the prophet, so on and so on.
The Gentiles who did not recognize the creation of God as a superior being with the proof of God's hand before their very eyes were sent no one. They died in their sins and they will not have an excuse on judgement day.