Scientifically we are made of molecules of carbon water etc.. and matter cannot be distroyed. so when we die our body is decompsed in to molecules and integrates in to nature. Some time in future some other living being uses these same molecules as food and grows. As we eat now. If you think what w eat now is nothig but molecules in its complex form. which may have been in the body of some other living being some time in the past.

It looks crude way of explaing but actually for nature, human life not more or less precious than a dogs life. they both are same.

For your internal satisfaction you can have the concept of god, religion. But Nature is much more powerful than any god defined in any religion.

there is god but
there is no god as defined in religion. definetly god desnt look like human being. GOd can be defined as strength of matter and energy which takes different forms as it has taken one form called life on earth.
even lifeless rocks on earth show wonders of god.
may be on some other celestial body it can take other form.

science has discovered lot of things which human cannot see like xray, wireless communications. If god exisits as defined in religion science whould have able to figure it out.