Here we have Levites, ministers of service, who will be priests between God and the people, and the famous men who rebel against the authority of Moses. The direct judgment consumes these, and the fire of the sanctuary they would approach consumes them. Korah acted on all the congregation, but Moses in judgment, and Aaron in intercession afterward, when their hearts rise against the judgment or Moses as cause of it, preserve the people. The supremacy of Christ as Priest is established as being near to God, but thereon the priests, and He especially in the day of atonement, but the priests every day being thus brought nigh, have to bear the iniquity of the sanctuary. This is an important principle, it is not sin against the commandment of the law, but the iniquity of the sanctuary; but the communion of the sanctuary, chapter 18:10, is theirs, and everything that the Lord takes as His, but this as priests.
Remark how for the history of Korah is a point by itself, the coming into the land being fully assured in grace, at the end of the failures in faith of Israel, in the previous chapter. Korah, etc., is positive rebellion against the authority of God in the royalty and priesthood.
Note the contrast between Aaron's formal self-exaltation along with Miriam against grace, sovereign grace, and God's exaltation of the priestly position as alone holding the burden and enjoying the communion and God's food of the sanctuary—all was polluted to all unless cleansed by this consecration; chap. 18: 32. Thus the world, alas! through the Church firstfruits.
Note prophecy and priesthood never reach the place of sovereign grace even in the Church. The Church's own place is in Moses marrying the Ethiopian, and face to face with God, because it enters into the mind of God where Christ is.