Some versions of the Bible use the phrase chief priests. This is likely a descriptive label and not a title; they can best be thought of as leading priests.
One priest was selected to be the high priest, a position they would hold for life The first high priest was Moses’ brother, Aaron.
Jesus effectively changed the role of the priests. It’s through him that we no longer need a liaison to God, as we can approach God directly. As such, Jesus became our high priest, forever (Hebrews 6:20).
Also see Melchizedek.