Gemara: Rav Ami said: There is no death without sin.

Ein Ayah: The order in which Hashem formed His creations is that there is a continuous increasing in terms of their completeness. Once creation reached the status of man, who has a significant element of freedom to choose, the basis of the building of the levels of elevation is in regard to man’s moral status.
Therefore, if a person’s moral standing is incomplete and has not reached the point at which sin is not found, death is necessary so that the species can keep moving on in the proper direction. Only eventually will it be achieved that there will be people who are so morally complete that they have not committed any sin.
The moral shortcoming, as long as man has not reached the point at which he has eradicated sin, is not focused on sin specifically done intentionally, which is what can cause a person to be subject to a punishment of death. That refers to death based on an individual sin by chance. Rather, we are talking about a general lowliness that has not allowed getting to the point at which life is so high that it has no connection to sin. In any case, without any sin, death is not appropriate.