So glad you asked Neko! Relics reflect the Church's emphasis of embodiment. Catholic life and worship is peculiar in how matter is involved at every level. Every sacrament occurs through and within material. This is appropriate for human beings since we are also material. We don't just possess a body, we are a body. This of course coincides with the doctrine of the resurrection of the body. Since we are embodied beings, our final, perfect state will not be bodiless. As such, the bodies of the departed saints are not truly a sign of "death" for Catholics, but the new life to come. In recognizing that the body before us will be raised up on the last day, we turn in hopeful anticipation towards the resurrection of our own body. This orients us less to the saint himself/herself, and more to the One who will raise them and hopefully will raise us as well.