In the Old Testament, the role of the priests and the setting of the tabernacle were the centerpieces of all worship, sacrifice, and atonement for the people of God.
Through his ultimate sacrifice, though, Jesus put an end to this by atoning for our sins once and for all. He came near and made his home in us with the fulfilled promise of salvation and freedom through belief in him.
This makes Jesus the guarantor of a better covenant.
The former priests were many in number, because they were prevented by death from continuing in office, but he holds his priesthood permanently, because he continues forever. Consequently, he is able to save to the uttermost those who draw near to God through him, since he always lives to make intercession for them.
For it was indeed fitting that we should have such a high priest, holy, innocent, unstained, separated from sinners, and exalted above the heavens. He has no need, like those high priests, to offer sacrifices daily, first for his own sins and then for those of the people, since he did this once for all when he offered up himself. For the law appoints men in their weakness as high priests, but the word of the oath, which came later than the law, appoints a Son who has been made perfect forever.