Romans 1:14-15

14 I am obligated both to Greeks and non-Greeks, both to the wise and the foolish. 15 That is why I am so eager to preach the gospel also to you who are in Rome.

I suspect the foolish mentioned here refers to those society considers foolish. Jews looked down on non-Jews (even though they had been conquered by them). Philosophers and thinkers of this age spoke Greek and promoted Greek culture. The Romans in Rome quite likely thought they were superior to all others, because they lived at the seat of power for the Roman empire. All people would have found a reason to think poorly of Paul because of his connection with a group they themselves looked down on. Paul didn’t discriminate between Greek, Roman or Jew. He was eager to preach to all. Am I? All too often I don’t want to minister to anybody, I want to get my next task done.