Christ forgave people their sins before he actually laid down his life. Adam, Abraham, and Moses were all forgiven. Now we’re pretty sure that there is no sin that can be defined as mankind needing physical maintenance. God also healed scores people in ancient times without the reference to sacrificial death.
Where is death, enemy #1, in the scenario that permanently forgives sins, heals bodies, and relieves demonic oppression?
Christ died to save us from our sins, not from sickness, and not from poverty or lack of this world’s goods. He saves all or none at all. New bodies are a resurrection morning event for everyone. He heals all or none at all. Matthew 8:16-17 is not about atonement, but divine generosity, identifying with human humiliation and relieving human physical and demonic oppression. The remission of sin is the only stated goal for Christ’s death on the cross.
That evening they brought to him many were oppressed by demons, and he cast out the spirits with a word and healed all who were sick. This was to fulfill what was spoken by the prophet Isaiah: He took our illnesses and bore our diseases. Matthew 8:16-17