With Great Power Comes Great Responsibility

  "why should a divine being (hypothetical) do something we have the free will to do for ourselves and choose not to?"

--

 We don't actually have Free Will. 

But I'm willing to pretend we do; for the sake of argument.  

There are some statements where it makes sense to speak of:

all of humanity 

as a collective "we".

 Granted.

But the issue raised in the OP

 is not one of those times. 

[for reference]

For all of recorded history,

there have been an unknown % of individuals

who ~did what they could~

and found it was never enough.

There were always even more people 

who just only randomly tried to help heal the world and prevent further tragedies.

 Most were too busy just trying to survive.

And there was always some who just went around causing tragedies.

--

Until humanity became literate,

most people were pretty clueless about the struggles of the larger whole.

Until most people were on the internet, 

most people were unable to coordinate in real time with people around the globe, towards global initiatives.

Even now, science is still in its infancy.

So we simply don't know how to prevent and cure most forms of pointless and extreme suffering.

And for every individual who TRIES to convince entire societies to prioritize those fields of science,

there are billion$ corporations, and corrupt politicians, and a largely apathetic/under-educated society in the way.

 And it doesn't matter how loud Responsible People yell, their voice is drowned out. 

 It doesn't matter how hard they push, those on the other sides of those walls push back harder.

No individual who *does their best* 

is guilty of being a part of a "we" who doesn't.

No "God" could justify letting the Morally RESPONSIBLE suffer at the hands of the willfully evil.

No "we" who is limited in what we even CAN do 

is guilty of not doing more than we can do.

No child 

is guilty of ANYTHING; 

when they get bone cancer, or kidnapped and tortured. 

No innocent parent is guilty of LETTING that happen.

 

No human is guilty of being born ignorant.

 That's unavoidable.

No human is guilty of being wrongly "informed" by crazy people pushing nonsensical conspiracy theories ... but then MISTAKING that as a real education. 

 Vulnerable minds are only vulnerable per biology  and environment. So they don't know they need to get out of there and get real help from sane adults.
As a result,
they end up voting and speaking contrary to reality; and causing real harm.
But they do not realize they are doing that.

The WHOLE OF HUMANITY 

does not yet HAVE as much power as it would NEED, in order for you to even build your argument without fallacy. 

Nor is everyone "deciding" not to try to fix things.

IF (only IF) there is a "God", 

then It/He/She/They/Whatever 

had the power to DESIGN humans to be less faulty. 

It also had the power to DESIGN a world where not nearly so many things even CAN go wrong.

and 

where no human MIND can EXPERIENCE nearly as much suffering as we do under sufficiently adverse circumstances. 

Humans didn't create most forms of super-harmful microorganisms. 

Humans didn't create a PLANET where tectonic shifts cause volcanos and earthquakes to erupt without warning.

Humans can't control the weather.

Humans didn't create an ECOSYSTEM full of destructive parasites and hungry predators who kill prey by horrifically EATING THEM TO DEATH. 

 And we're a LONG ways off from knowing how to resolve that. 

Humans didn't create an ecosystem full of super-toxic soil, water, and plants ... which look, feel, smell, and taste FINE ... until we fall over in extreme agony from exposure or ingestion and begin to slowly die. 

Humans didn't design faulty human genetics. 

Humans didn't even know we HAD "genetics" until pretty recently. 

So we didn't even realize there was anything like that to LOOK FOR. 

And we still don't know how to fix that either.

If there is a GOD, 

they set us up for all of that.

It would mean they created stupid little kids

and created a super-deadly world-sized garden

and

then just let countless humans AND ANIMALS 

suffer horrifically;
 and in many ways that were of no benefit to anyone.

All so that random individuals would eventually discover a tiny bit more DATA,

to allow us to EVENTUALLY solve the OCCASIONAL problem;

while countless still suffer pointlessly. 

You can't really justify saying we are ALL guilty of what we didn't have any control over;

NOR "all" guilty of what only sociopaths and idiots prevent us from accomplishing. 

---

WITH GREAT POWER 

COMES GREAT RESPONSIBILITY. 

If there is an ALL-POWERFUL BEING,

then they have at least MOST of the responsibility.

Responsibility scales upward with power;

not downwards. 

This shouldn't be a hard concept to grasp.