Being fantasy free, this is how I answer the question.
First we can see that lives matter to immediate family and a few others. Just by observing we can see that certain people are fond of one another.
On a larger scale, things are not that obvious. To get started, we have to try and answer a basic question. What is life? Even the most brilliant minds are not close to answering that question. There are lot of platitudes and assumptions offered but the basic question, to date has no answer.
We don’t know what life is. If we don’t know what life is, there is no definitive way to say that the life of any one person or the lives of all of us together matter. World wide it is estimated that 151,600 people die per day. How many of those lives matter?
Does your life matter? I am sure it matters to your mother but I am not sure it matters to very many other people. The only thing I can say for certain is that your life matters to others if you find a way to make it matter.
Chances that your life matters to strangers in government are not very good.