If matter cannot be created nor destroyed, do our body composed of the same matter as matter formed 13.82 billion years ago when the universe was created?
Matter can be created and destroyed. Particle accelerators do that all the time. Conservation laws do apply, of course, but what is conserved are things like energy, momentum, angular momentum, or electric charge, not “matter”.
That said, it is not easy to create or destroy matter, which is why the world around us seems fairly stable, and which is why we need big, complicated machinery to create or destroy matter. And yes, a good portion of the particles from which you and I are made have been around for 13.8 billion years.
That is to say, protons and electrons have been around. Not neutrons. Free neutrons are unstable; they decay after about 10 minutes on average. The neutrons in your body were produced much later, mostly in the hydrogen fusion process that goes on inside stars.
This is also true for all heavier elements. Essential building blocks of life: atoms of carbon, oxygen, nitrogen, etc., were all produced inside stars. Heavier elements in particular were produced in spectacular astrophysical events such as supernova and kilonova explosions.
In short: When you drink a glass of water, the hydrogen atoms in those water molecules are mostly 13.8 billion years old. The oxygen atoms are billions of years younger, and come from the interior of stars much heavier than the Sun.
Credit: Viktor T. Toth