Jesus tasted death for us because 1) He is God and more powerful than death; 2. Because he was totally without sin, he was not liable to die, so his voluntary death became the perfect and acceptable, atoning sacrifice for the sins of mankind; 3. Jesus' death was arranged by Satan and his minions, who had absolutely no power or authority to do so. As a result, Satan forfeited everything that he had earlier gained by Adam's fall from God's grace; 4. The end result of all this was Jesus being named the new and sinless head of all mankind, Satan being left desolate, sinful mankind being reconciled with God, and the Gates of Heaven being opened, once again. Because he is man, the grace Jesus obtained for us on the cross accrues to the benefit of all mankind. Because he is God, the grace Jesus obtained for us is infinitely powerful and eternally effective. There's more, but that should get you started.