Many bore responsibility, including each of us. A prayer to God in Acts 4:27 shows a wide range of blame: "For truly against Your holy Servant Jesus, whom You anointed, both Herod and Pontius Pilate, with the Gentiles and the people of Israel, were gathered together . . ."
So it wasn't just the rulers, it wasn't just the Jews, it wasn't just the Romans who are implicated in the death of Jesus. They all had a role—as did we. Also playing a major part in this was the deceiver and enemy of God, Satan the devil, the ruler of this world (John 14:30). Paul tells us that humanity is in "the snare of the devil, having been taken captive by him to do his will" (2 Timothy 2:26). So he obviously led the people involved in killing Christ to do so—as He has also led all of us into the way of sin, making Jesus' death for us necessary.
But notice that the prayer cited above from Acts 4 immediately goes on to say to God that the various people were all gathered against Jesus "to do whatever Your hand and Your purpose determined before to be done" (Acts 4:28). Clearly, this was God's plan all along. In fact, Isaiah 53:10 says, "Yet, it was the Lord's will to crush him with suffering . . . [making] his life a sacrifice for our wrongdoings" (God's Word Translation). It was God the Father who decreed concerning Jesus, "Awake, O sword, against My Shepherd, against the Man who is My Companion,' says the Lord of hosts. 'Strike the Shepherd . . .'" (Zechariah 13:7).
We can further see that it was God's intent through the sacrificial system He gave to ancient Israel. Jesus came in fulfillment of it, His death being obviously predetermined by God.
Moreover, Jesus Himself said: "I lay down My life . . . No one takes it from Me, but I lay it down of Myself . . . This command I have received from My Father" (John 10:17-18). That is to say, He would not have died without His and His Father's willingness and orchestration of events for it to occur.
Thus, ultimate responsibility for Jesus' death lies with the Father and Himself. They determined it would happen. In fact, They created man with the possibility of sinning to begin with, and They assumed responsibility for sin through the plan of Jesus' sacrificial death. That's why the apostle Peter, in explaining that we are "redeemed . . . with the precious blood of Christ, as of a lamb"
(1 Peter 1:18-19), immediately states that "He indeed was foreordained before the foundation of the world" (verse 20). While God gave people free will to choose to sin, which would result in the consequence of death, His plan for them provided a sacrificial offering in their place so they could be forgiven of their sins and reconciled to Him.
None of this, however, excuses human beings for sin. We all bear responsibility in the wrongs we have done. In fact, we must realize that our sins are what necessitated the death of Christ—so that all of us share blame for killing Him. Yes, you, me, everyone.