Hebrews 2:15

and deliver all those who through fear of death were subject to lifelong slavery.
(Hebrews 2:15 ESV)

Jesus frees us from the fear of death, from death, from a lifelong fear of not knowing freedom, not knowing comfort, not knowing peace. Why? Because God is our friend and our protector. And everywhere we are under the protection of our Savior.

Hebrews 2:14

Since therefore the children share in flesh and blood, he himself likewise partook of the same things, that through death he might destroy the one who has the power of death, that is, the devil,
(Hebrews 2:14 ESV)

Just as those who are to become the adopted children of God have the nature of man, Jesus took on the same nature as them, that by dying he might bring into subjection the devil, who has dominion over death. Death marks an end, but Jesus changed that by rising from the dead to rescue man; to restore him to life; death is now unknown to man; his redemption introduces a state in which not another one would ever die.