Hebrews 4:14 – 5:6 (ESV)
14 Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession. 15 For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin. 16 Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need.
1 For every high priest chosen from among men is appointed to act on behalf of men in relation to God, to offer gifts and sacrifices for sins. 2 He can deal gently with the ignorant and wayward, since he himself is beset with weakness. 3 Because of this he is obligated to offer sacrifice for his own sins just as he does for those of the people. 4 And no one takes this honor for himself, but only when called by God, just as Aaron was.
5 So also Christ did not exalt himself to be made a high priest, but was appointed by him who said to him,
“You are my Son,
today I have begotten you”;
6 as he says also in another place,
“You are a priest forever,
after the order of Melchizedek.”
JESUS IS THE GREAT HIGH PRIEST
Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession.
The high priest is chosen by God. (Heb 5:1, 4)
Then bring near to you Aaron your brother, and his sons with him, from among the people of Israel, to serve me as priests—Aaron and Aaron’s sons, Nadab and Abihu, Eleazar and Ithamar.
Big Idea: The high priest is simultaneously one of the people, a servant of the people, and the representative of the people before God.
So Aaron shall bear the names of the sons of Israel in the breastpiece of judgment on his heart, when he goes into the Holy Place, to bring them to regular remembrance before the LORD.
The high priest has access to God’s presence.
I will dwell among the people of Israel and will be their God.  And they shall know that I am the LORD their God, who brought them out of the land of Egypt that I might dwell among them. I am the LORD their God.
For a tent was prepared, the first section, in which were the lampstand and the table and the bread of the Presence. It is called the Holy Place.  Behind the second curtain was a second section called the Most Holy Place…  These preparations having thus been made, the priests go regularly into the first section, performing their ritual duties,  but into the second only the high priest goes, and he but once a year, and not without taking blood, which he offers for himself and for the unintentional sins of the people.
Hebrews 9:2-3, 6-7
The high priest offers sacrifices of thanksgiving and atonement for sin on behalf of the people.
Hebrews 5:1, 3
And Aaron shall present the goat on which the lot fell for the LORD and use it as a sin offering,  but the goat on which the lot fell for Azazel shall be presented alive before the LORD to make atonement over it, that it may be sent away into the wilderness…
Jesus is the better high priest. Hebrews 4:14
He himself bore our sins in his body on the tree, that we might die to sin and live to righteousness. By his wounds you have been healed.  For you were straying like sheep, but have now returned to the Shepherd and Overseer of your souls.
1 Peter 2:24-25
Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.