Elemental world building for all to use, what me Robert Mitchell Livingston is very good at creating.
To create true immortality, the beings up all the way of all that exists build the particle below the particle that the currently level of beings can build. Think in terms of war or heaven, during war on Earth if your body dies that gluon level soul that saves all information of who you are is pulled into another body in The United States of America Armed Forces, creating levels of fall back points so a single being can fight again and again. If the gluon soul is defeated, The Milky Way Galaxy then pulls in the soul or level negative 3 particle that overlaps your entire particle into another body, say mid way towards the center of The Milky Way Galaxy. Creating another fall back point to fight from by layering the levels of particle with souls that save all the information of who you are.
In times of non war, if you die the same thing happens just not by The Armed Forces but by The Life Forces, falling you back to the next level of existence. From Earth to The Milky Way Galaxies next Life point of fall back. If The Milky Way Galaxy is wiped out or you die within it, then again you fall back to the next strategic Armed Forces point in War, or to the next fall back point of life. These are fall back points because you are supposed to grow up through existence in one body or grouping of particle that you build on the particle level you are at and then down and down as you take control of each soul, which is yours once you can take control of it from the next fall back point, or the soul is taken out and base particle put in so you can build anew dependent upon on who is in control of that particle level of soul inside you.
The more built your body or the lower level of which particle can be built makes dying harder and harder, and almost impossible the farther you go up all of existence because life means more and more and takes more and more to create. When simply damaging protons, neutrons, and electrons on this level can result in death, the farther you go up existence the more particle layers down inside you have to be damaged to result in death because entire layers can be destroyed and you would still be fine just need another body for your soul to inhabit. Which would be a loss of that layer as if dying on Earth and having your gluon soul sucked into a body by The United States of Americas Armed Forces in a government facility on Earth to then be put in another body. Creating layering of souls on a single planet instead across all of existence itself were you would have to start again far from all you know or with only the souls that went that direction in existence dependent on who has control of the soul below the layer that died. Creating true immortality for life forever.