Saints are persons that are an example and inspiration to the faithful. They are not perfect, which distinguishes them from the Sefrim. They are human, like you and me, and have most of the time also lived sinfully for part of their lives. But at some point, they have turned to God and done things that can inspire us all, be it acts of mercy, intercessions or even miracles. To make them more relatable to us, we can contemplate their relics - seeing their remains is a powerful reminder of their human nature, and a call to us that living a saintly life is within reach of all.
I have been asked a very strange question today, namely whether a living person can be a Saint. That is not normally the case: people can be living a saintly life, but they are canonized after death and after performing miracles from the hereafter. That being said, there are rare exceptions that have been historically known, as some Emperors were declared Saint by popular acclamation even before their death. And sometimes, well, if venerable persons return from death such as Saint Jamyl, they are recognized as instruments of God during their (second) life.
The procedure is that one or more bishops petition the Theology Council to have someone that is deemed worthy of veneration as Saint recognized officially. Before the official recognition, it is allowed that the faithful of that bishopric already venerate the candidate-saint. Very often this is a local folk-saint that is already a local "hero" to the faithful, and their bishop wants to make the cult of that folk-saint officially recognized (with the added economic benefit of pilgrims being drawn to the shrine of the saint).
It is not written explicitly that the candidate-saint should be deceased when the petition is submitted to the Theology Council, though I imagine that a petition for a living person would probably be rejected at the end of the long process. And it is only when the process of verification and canonization is complete, that the saint will be recognized throughout the Empire. Up until that time, the faithful outside of the petitioning bishopric have to follow their own conscience whether or not to consider the candidate-saint a true saint.
