We are born, we die and then we are born again. It is beyond control in which plane of existence we will be reborn; it depends on the kamma which produces the patisandhi-citta (rebirth-consciousness) after the cuti-citta (dying-consciousness) has fallen away.
At this moment we are living in the human plane. Human life, however, is
very short. When this life is over we do not know in which plane we will be
reborn. Most people do not like to think of the shortness of human life; they
are absorbed in what they experience through the sense-doors and on
account of these experiences they are happy or unhappy. However, we
should realize that happiness and unhappiness are only mental phenomena
which arise because of conditions and fall away again. Our whole life is a
sequence of phenomena which arise and fall away again.