Was Peter greater than other believers in God's view?
No. In God's view, Peter was no greater than anybody else. God accepts no man's person, and those who seemed to be somewhat no longer had preeminence in God's dealing with the human race. Paul, under the Holy Spirit's inspiration, emphasized this, showing their earlier authority was slipping away.
Les explains that Paul, by inspiration of the Holy Spirit, was not simply getting back at the apostles. Scripture repeats the point shortly for emphasis. The men who seemed to be somewhat no longer had the authority and preeminence they had enjoyed in the early years and early Acts; it was slipping away. God accepts no man's person, so in God's view Peter was no greater than anybody else. Those men added nothing to Paul because they had no comprehension of the revelations Paul had received from the Ascended Lord. They knew Jesus in the flesh, and 40 days after His resurrection, but they knew nothing of the Ascended Lord, from whom Paul received all.
But of these who seemed to be somewhat, (whatsoever they were, it maketh no matter to me: God accepteth no man’s person:) for they who seemed to be somewhat in conference added nothing to me: