Gold is the gift for a king. Frankincense is the gift for a priest. It was to be used in the Temple and in temple sacrifices. The function of the priest is to open the way to God for men and women. He opened the way for all of us into the very presence of God.
Myrrh is the gift for one who is to die.
Myrrh was used to embalm a body. Now let s suppose that we were the king at that time. Now Herod is an interesting character. He reigned from 47 BCE until his death in 4 BCE and was called Herod the Great. He built the Temple in Jerusalem and kept the peace, so he was great in some sense.