There was little sophistication in post-Roman Britain, although, as you know, some of the artwork and literature of that period is quite exquisite. Travel was immensely difficult and dangerous. Lone travellers feared for their lives, and paganism was strong and aggressive. So, indeed, were some to the Christian missionaries. But some things, perhaps, are not very different.
People are people.
The Gospel is the Gospel. Although we often talk about a spiritual thirst out there in the world, it has never been any different, and the Church has always struggled to find the right way of meeting those needs. Part of our calling, as our ordinal puts it, is to proclaim afresh for every generation the faith which is uniquely revealed in Holy Scripture and set forth in the catholic creeds. So if from time to time we struggle to find the most effective way of preaching the Gospel, we are not alone. It has always been so.