ArrJay, you are asking intelligent questions, which is quite rare...
Yes, it is said that we come here to learn. But it's just this - a saying. I would advice you to try investigating actual observable data we have. It's true, we are incarnated into human bodies, that have a life on their own. They function based on survival instincts, evolutionary programs, that most people even don't realize, but identify as themselves, although it's just their body. Also we are born so weak, so easy to manipulate, that we rarely live life of our own. We live to please our parents, our partners, our children, the society, the gods... So if we learn something on this planet it would be how to survive physically (and mentally)... As you said, civilized life, with potential for learning represents very tiny periods of this huge planetary history. Most of the time you just get born, kill others to survive, have sex to propagate the species, and die. How many times this must repeat? I would argue, that we passed the golden age of the human civilization which ended 1900 with the world wars. The modern life is technologically advanced, but psychologically inferior. Just pick and compare any music, literature, philosophy... We live in the late stages of the Roman Empire (i.e. US in its modern analogue). To put it bluntly, what people nowadays learn about love, is to wear a condom...
Do we reincarnate on other planets? Most don't... Check out people that had NDE. For example in youtube, there is a channel called billsvideos123. But listen VERY CAREFULLY. Think with your own head what these people really experienced, since observation and explanation are two different things...
I will tell you my vision of what is happening, although I'm from the minority. We, as spiritual beings come from something that we call the Source, also the One. It's the real God, although 99.99% of the people worship other things as gods. We all have the potential to create. The Universe is full of such creations, and there are probably other Universes governed by completely different rules. We not only create worlds, but also play in them. Our Solar system is just one small such world and playground. However, our Sun has huge ego. If you know from astrology, the Sun is your ego. When you die, the Sun sucks your soul and then tricks you to reincarnate again in its solar system. This is why most people worship the Sun as their god. Even Christianity was created by Romans as a hybrid between other religions and the existing cult to the Sun. Do you know what this symbols is?
Do you know why we rest on Sunday? Do you know why we celebrate on December 25? Or Easter?
Anyway, if you look around, you will understand that the central deity of this planet is the Sun, which is really not that surprising... This deity doesn't have just physical aspect, but also spiritual. And as an egoistic entity, it preaches it's own version of spirituality. And here one bracket - spiritual doesn't mean necessarily good, perfect, higher understanding, etc. This is how to promote your own version of spirituality as the only one... In reality, anything is allowed on the spiritual plane, since this is love - allowance. However, our Sun is immature, and doesn't like us free. It keeps us in its matrix that says that Sun is the only god, although it governs only our physical bodies.
About learning, here is something simple to understand. The Source, created us just to be, out of its love. Whether we learn, and what we choose to learn is up to us. Nobody can force you to learn anything. Although learning is important, it's not the center of existence. And this is easy to see, especially on this planet, so few people actually learn... So the idea that we always have more to "learn" is a trick to keep you here. Yes we have, we always have, but who is saying we must learn it here, in this particular life matrix? Who told you that? Well - as you can see from the NDE - the Sun :)... NDE shows so well, that these people meet the spiritual Sun. Not the Source which is in you. The Sun plays an interesting game, no doubt you can learn something from it. However be very careful when you let external beings dictate your believes... What I'm trying to say is that you will never exit this playground here if you don't find it really in yourself.
I've heard for myself, that my solar system died, and I had to go somewhere. This is another important aspect, that this system is opened to anybody. This is why people here are so different, even though the physical bodies are relatively the same. I'm not sure if this is true for all solar systems. Most probably - no, since most planets seem to be collective. But when they run their course, what happens to these souls? Maybe they start to develop as universal souls on special solar systems like this one. We are probably learning about the ego on this solar system, learning to walk again so to speak, but by ourselves, since there is nobody else really out there for you. It's actually more difficult then it seems, even our Sun probably plays its own ego game... Just my guess. I think however, that at any point you should have the choice to return to the Source, and the fact that people with NDE talk about a deity that tricks or forces them to reincarnate, that this deity is external and creates other external objects based on your believe system and human relatives... What that this tells you...