Nonsense. So when Paul erroneously claims (not knowing of North America, South America, and vast populations far to the east of Persia in Asia and far to the south of Egypt in Africa) that the gospel had been preached throughout the whole world (e.g. Colossians 1:23, Romans 1:8, etc) then that means everything else in the bible is false?
How does that follow?
The Gospel is in Genesis 3 and would have been proclaimed by the first humans to those who followed into all parts of the world. We may think this portion of the biblical texts to be a recent invention, when in fact it has been part of common knowledge from the beginning. The Apostle Paul knew as much.
As for the claim that the biblical texts are either 100% true or 100% false, I tend to believe they are 100% true, while we are inclined to consider them true only when it suits our fancy.
Missionaries have on several occasions made the statement of prophecies of "white men" who would come to the village, and that the village would in turn accept the God of the white men that came. Sounds an awful lot to me like someone had been there before, "weather in flesh, or in spirit."