about the conservation of energy theory...?

Your body doesn't have that much energy ( from a physics point of view ) as you think. The highest energy your body posseses is the thermal energy of 36,6°C. This thermal energy is given off to the environment because the law of entropy, after you die.

Then, your body has potential energy at heights. So if you die somewhere above the ground your body carries potential energy because of earths gravity. When your body if brought back to ground level this potential energy drops to zero. This potential energy is converted in kinetic energy to bring your body down.

Your body also is capable of having kinetic energy, but you don't have this after you die so we shouldn't take this in account.

The last thing your body has is the INTERNAL kinetic energy, this is the energy of every cell moving, blood flow, etc. After you die, your blood flows stops, and your cells die because of lack of oxygen. Because every cell is dead you can see it as dead matter and apply physics to it very easy. It stops moving because of the friction with other cells. So simple as this.

Kinetic energy is energy of motion, so it leaves our body whenever we stop moving. Sometimes that gets transformed into potential energy (if for example we use our motion to wind a clock or push a weight up a hill); but almost all of it turns into heat which warms up our surroundings a little bit.

The thermal energy in our bodies dissipates into the atmosphere (warming up the atmosphere a little tiny bit) as our dead bodies cool down. (Actually, our bodies contain thermal energy as long as they remain at a temperature above absolute zero. So some thermal energy remains with our bodies for as long as our bodies exist; or remain with the decay products a our bodies decay).

Our bodies also contain a certain amount of chemical energy, and the fate of that energy depends on what happens to our bodies after death. If we're cremated, our chemical energy helps make the fire hotter. If we decay "naturally," the chemical energy goes into the soil, possibly acting as nutrients for other life forms. If we're "preserved", a lot of that chemical energy stays inside our bodies indefinitely.

"Spiritual energy" -- whatever that is -- is not energy in the sense that physicists use the word, so the physics principle of conservation of energy does not apply to it.

Yes. Exactly your body cools warming the environment and that energy gets radiated into space and dissipates

Without life processes your body rots (ashes to ashes and dust to dust)