Peter to his credit recognized his error and recalled the conversion of Cornelius, and other Gentiles, but the revelation was given to Paul.
Acts 9:15 But the Lord said to him, "Go for he is a chosen vessel of Mine to bear My name before Gentiles, kings, and the children of Israel.
Gal. 1:12 For I neither received it from man, nor was I taught it but It came through the revelation of Jesus Christ.
Gal. 2:7 But on the contrary, when they saw that the gospel for the uncircumcised had been committed to me, as the gospel for the circumsized was to Peter.
Please explain further as I am not sure what error Peter recognized. In the story of Paul’s conversion, it is to Ananais that the Lord reveals Paul’s mission. We do not hear Paul speak of this special mission until later.
The whole story seems to indicate that Paul was converted by Jesus, and then Paul was accepted by the others, a form of imprimatur. He preaches for a time in Damascus, but then seems to go on a sabbatical of sorts for three years. After that time, he returns and spends 15 days with Peter after which he begins his ministry.
Paul sets himself apart from the others yet claims that they accept him and his reception of the Gospel. So, he sees his mission as different than theirs, but still teaches that the Gospel he received is the same as that of the others.
Now, if we pay close attention to the Gospel, we hear Jesus tell them to go out to ALL the world making them disciples and baptizing them. So the word ALL would seem to include Gentiles.
So, it is a bit complicated, but we have God giving the initial reception of Gentiles to Peter, who then brings it to the council in Jerusalem and then Paul declaring himself the Apostle to the Gentiles in Galatians.