How do we know Jesus' priesthood is better than the old covenant?

Jesus' priesthood is emphasized as better than the old covenant in Hebrews 7, where it is stated that He has an unchangeable priesthood (Hebrews 7:24). The Levitical priesthood was temporary and flawed because of the death of the priests, necessitating continual replacements. In contrast, Christ's priesthood is established by divine decree, transcending human lineage, thereby ensuring that He remains our mediator forever. This eternal and perfect priesthood means that believers have continuous access to God through Christ, who lives forever to intercede on our behalf.