84 lacks of Births Before "Human being"

There are 84 lacks of Births Before "human being",
as written in the holy books according to the saints.
A soul has to pass through 84lacks of births to reach the birth of "Humanbeing",
According to the saints the birth of "Humanbeing" is the golden chance for the soul to come out of this circle of death & birth,
If this chance left than once again one has to face the problem of 84 lacks births & deaths,
Some creatores on this earth have age more than 2000 years like some trees, so how long it will be to pass 84 lacks of births, it can take millions of years,
So according to the saits of acient age one should not leave this golden oppertuniety for the soul to come out of this circle of death & birth.