Throughout the first four verses of Hebrews, the author provides multiple propositions with regard to Christ that rightly portray His nature as both fully human and fully divine. As a result, we see the supremacy of Christ displayed, which will form the basis of comparison between Christ (as Son of God and Son of Man) and the angels, Christ and Moses, Christ and the Levitical priesthood, and so on. So, because of who Jesus is in His Person, we will see that Christ is "better than" in all of these comparisons. Additionally, and intimately related to this point, the writer foreshadows the argumentation to appear later in the epistle by implicitly alluding to the various roles in which Jesus was and is active. Namely, in these four verses we see Christ as prophet, priest, and king. And, as the writer intimates, it is not merely the fact that a single individual operated in each of these three roles that is significant. Rather, because of each part the dual nature of Christ coupled with His absolute and voluntary obedience to the will of the Father, we see the expectations of these roles dramatically fulfilled in who Jesus is/was and what He does/did. Jesus is not merely the last in the line of prophets, the last in the line of priests, and the last in a line of kings; Jesus is in a sense the Prophet, the Priest, and the King to which others pointed but were insufficient in their capacity to effectuate and consummate.
Though the writer does not yet explicitly designate Christ as active in each of these offices, the implication is clear. "God, after He spoke long ago [...] in the prophets [...], in these last days has spoken to us in His Son," the ultimate Prophet who "spoke the things as [His] Father taught Him" (Hebrews 1:1-2; John 8:28). Not as the priests who repeatedly offered sacrifices as a covering for sins, obligated to stand because their work was never fully complete, Jesus is the Priest who conclusively "made purification of sins" and has "sat down at the right hand of the Majesty on high" (Hebrews 1:3). Moreover, as the kings of Israel were limited in their reign by physical constraints, Christ the King has been "appointed heir of all things," and "His kingdom will have no end" (1:2; Nicene Creed; see also 2 Peter 1:11).
If such things are so, then we ought to see and realize how much we can trust in Christ, for He is the God Incarnate. Indeed, because of these things, "He is able to save [...] to the uttermost [those] that come unto God by Him" (Hebrews 7:25, KJV).