If you equate death with sinning, then yes, you're going to come to the dead end of JW theology(pun intended) which teaches not that belief in Christ saves the intangible spiritual aspect of man, the soul, if you will, but only serves to make fodder for an earthly resurrection to a physical existence that sounds good, but offers hardly more communion with the spirit of the Divine than we have now in our present earthly form.
Christianity offers literal spiritual oneness with God upon leaving the physical body, which would have been received variously by the various Jewish sects that Christ spoke to, and also by pagans that Christians later spoke to. It's likely that many pagans would have recognized the desire to be one with God in ways that Jews would not have, and vice versa.
It can either be considered a spiritual progression or regression, as many earlier religions believed there were various ways to be ONE with God, or the Gods, in many differing ways, by various ritual. It is not actually a new thought, not even the idea of atoning blood of a God buying our souls is a new thought, it existed before Christianity and before Judaism too.
But, Christ did represent a living embodiment of that very old and persistant spiritual concept, that through the blood of a divine being, we ourselves might become one with God.
That makes it significant for those who believe it, and isn't that what belief is all about? We're always looking for ways to express that intangible that is spirituality inside us in meaningful, outward ways. Hence, ritual, sacrifice, atonement, but the epitome of all of that is to attain oneness with the Divine.
However, JW doctrine only allows for a select few to attain that. Why deny it to the majority? The only conclusion I can draw is that it is a controlling device, and keeps the masses "in their place" by letting them know that they will never be quite as "divine" as the people in control of the religion.
It's one of the defining characteristics of almost every highly controlling cult. "You can only get to God through us."
Mainstream Christianity offers union with God who is embodied by Christ directly, more or less. There's no FTS "middle man".