I'm not a Mormon, so correct me if I'm wrong but:
"Spirit orbs" obviously referring to the "first estate" or, our existence as spirit children or spirit people, whatever we want to call them. Souls even.
Words matter. Spirit children, spirit people, souls... those all have different connotations than "orbs". It's like if I call a yarmulke a beanie. Yes, they are similar. But the connotations are very different.
The "first estate," is like the pre-life part of our lives. Our life here in the mortal realm is the second estate.
Yes, you got that right.
Back when we were in the first estate, we lived on Kolob with God.
Kolob isn't where God lives. Heaven is. About all the LDS scriptures say about Kolob is
"And I saw the stars, that they were very great, and that one of them was nearest unto the throne of God; and there were many great ones which were near unto it; And the Lord said unto me: These are the governing ones; and the name of the great one is Kolob, because it is near unto me..."
https://www.lds.org/scriptures/pgp/abr/3?lang=eng
So Kolob is apparently a star that is in some sense near to where God lives. Since I view God as not being limited by our three dimensional universe, I myself am not quite sure what "near" means in this context. And while it's true that sometimes LDS poetically refer to Kolob as being where God is (most notably in the song, "If you could hie to Kolob"), no LDS that I know would say "We lived on Kolob with God". All LDS that I know would say "We lived in heaven with God".
Our spirit bodies were stuffed...
As someone else has mentioned, "stuffed" isn't really the typical word.
... into our human bodies, but in the process, all memory of the previous spirit life was lost, because our human bodies don't have enough space or something.
Not sure what you mean by that last bit. Doesn't match any LDS doctrine that I'm aware of.
Kolob, as far as I understand, is where god lives with his wives and spirit children who haven't been stuffed into physical bodies yet.
It's barely LDS doctrine that God has a single wife, let alone multiple wives. Sure, I'd bet you could find statements to that effect by Brigham Young in the hey day of polygamy, but that is certainly not canonized doctrine.
Again, I'm not criticizing, and I hope Mormons will correct my misunderstandings of their beliefs, but that's what the picture is clearly referring to.
Well, yeah. But if you are going to criticize something you should not make several glaring errors in the process. Otherwise you look like an idiot.