Why are we here on Earth?   Why is there so much struggle here?
Where do we come from?   Is it important to know the answers to these
(and similar) questions?   Yes, of course.   By knowing the truth, we
have an understanding of what is really going on.   By having that
understanding we know who we truly are, and how to end the struggle.

David Hawkins said that this world is the perfect environment for spiritual development.
Each individual has to make choices between loving and unloving constantly; this world
is the perfect purgatory.   In this world it is possible to advance spiritually
very rapidly, and also to fall spiritually very rapidly.
When a lot of neuro-emotional issues are cleared via NET (Neuro-Emotional Technique),
it becomes more understandable how this is so.
There used to be a period of innocent harmony on Earth.
It didn't last, however, because there was lack of spiritual maturity.
As David Hawkins said, and NET confirmed, the souls out of lack of maturity
chose/did things that were not congruent with the Divine, out of curiosity
and naivety, aided by negative energies that gladly brought (and bring) down
everything positive/loving.
At that time Divine Guidance was available, at least initially.
However, it got lost rather quickly when overshadowed by unhealthy, unloving
stuff that resulted from the curiosity/naivety.   One of the main
contributors to the decline was alcohol.   "Here, try this drink,"
a temptation comes. "It's lots of fun and you may just feel a slight buzz."
And so alcohol was tried - one of the major contributors to the decline and
being cut off from Divine Guidance.   Still following this example, after
drinking alcohol, its violent negative energy fragmented the energy of the soul,
contributed to blocking Divine Guidance.   Now the soul found itself fragmented,
unprotected, naive, and easily seducible by negative energies.   And look at
the history, and even the current state, of the world as the consequence.
To return to the now mature pure loving spiritual state, loving and healthy
choices need to be made and loving and healthy ways to be followed,
such as promoted/taught by enlightened masters, such as Dr. David R. Hawkins, Osho,
Ramana Maharshi.   In addition to that, stopping ingesting toxins (such as
alcohol, coffee, pork, mercury), supplying the system with high quality nutrition,
and other good health boosting ways are vital.   The page Good Health Trinity mentions the universal basics of good health.

So this planet can be seen as a farm to grow crops.   The crops
being the souls.   This farm has the perfect soil to grow everything
from the most pesky weed to beautiful flowers.   Every now and then
the fields get too full with weeds and rocks and need to be harvested, ploughed and
started anew.   In other words, every now and then humanity - the way it lives -
becomes unsustainable, things get scrapped and a new cycle begins.
Yes, this is not the first time human society has been on Earth, and not
the last one either.
Seeing it joyfully, that souls are given a loving opportunity to evolve,
which includes making mistakes, is very helpful.