What was the relationship between Aaron and Jesus?
The Letter to the Hebrews compares Jesus with Aaron: God called both of them to be high priests. Hebrews 5:4-6
What the Bible says
Hebrews 5:4
Neither doth any man take the honour to himself, but he that is called by God, as Aaron was.
Hebrews 5:5
So Christ also did not glorify himself, that he might be made a high priest: but he that said unto him: Thou art my Son, this day have I begotten thee.
Douay-Rheims Bible (Challoner revision), public domain.
What the Church teaches
All the figures of the ancient priesthood are fulfilled in Christ, the one mediator between God and men.
Catechism 1544 · Catechism of the Catholic Church
Did you know?
Hebrews says that Jesus is a priest according to the order of Melchizedek, not according to the order of Aaron. Hebrews 7:11