Hebrews is a sermon-letter showing that everything in the Old Covenant — priests, sacrifices, the tabernacle — pointed to Jesus, who is "better" in every way. It calls a tired church to draw near with confidence, hold fast their hope, and run the race set before them.
Authorship has been debated since the earliest centuries — candidates include Paul, Apollos, Barnabas, Luke, and Priscilla. The letter itself is anonymous and the most honest answer is that we do not know.
“Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power.”
“For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit.”
“Now faith is the substance of things hoped for, the evidence of things not seen.”
“Let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us.”
“Jesus Christ the same yesterday, and to day, and for ever.”