The apostles in Jerusalem were seen as great leaders because they knew Jesus during his time on Earth. However, this did not give them more authority than Paul. What mattered most was Jesus personally choosing them (see 1 Corinthians 9:1; compare 2 Corinthians 12:11–12).
God does not show favoritism: The Judaizers (a group insisting on Jewish customs) likely thought the Jerusalem apostles' direct connection to Jesus was an advantage. Paul argues that favoritism is not in God's character (compare Leviticus 19:15–16; Deuteronomy 1:17; 2 Chronicles 19:7; Job 13:10; Psalms 82:1–2; Proverbs 18:5; Malachi 2:8–9).