Ok, I'll give it a shot.
I really don't care if you agree or disagree, it doesn't matter.
why are there 8 planets in our solar system? why not 10, 25, 6?
Gravity, dust and time.
We had more planets in the past, and we will have less in the future as orbits fail and planets get into orbital collisions, or the sun expands to cover them.
where were things before the big bang?
One thing you always see in nature, or the universe, at all levels, is 'cycles'. The big bang was just one part of a cycle, of something.
where are we going?
Everywhere, but only once we learn everything we can as humans and prove we are ready.
why are we going?
There is no other option. You only ever become better/wiser than you were. Even if it takes billions of years, everyone is on the same path to keep getting better/wiser eventually.
the universe is dark dark dark. Isn't that soooo scary?
No, nothing to be scared of. The universe is not dark at all, it's full of light, you just can't see all the light... yet.
If God created us, where did he get the time to create soooooo many things and sooooooo many creatures? He even created cats and tigers to differentiate themselves....
Maybe god created things that create an infinite number of other things, like maybe DNA. There is no need to create everything by hand one atom at a time.
With regard to the time needed... Relative to what, time is not a constant. It can be as fast or as slow as needed.
and most importantly, we humans' lives are very hard in this universe.
I don't think our lives are any tougher than we agreed to before hand.
We have no memory of this, but that is as it should be. You cannot truly learn without a clean slate to build on top of. You need to be free from the burdens of past mistakes long ago, they make you stubborn and are counterproductive to learning.
What's the point/purpose of lives?
To learn, to teach and to help. To be better than you were.
Sometimes, in order to learn fast you have to make lots of mistakes.
The point of lives is to merge you with a human mind and make something new that is imperfect and will make mistakes and learn quicker.