Eli5: Angels, Demons and Jinn - A Muslim-friendly Explanation

As-salamu alaykum - Christian friend here asking for a clearer picture of what jinn, angels and devils are in Islam. I’ll try to explain what I understand and ask a few questions. From my background we think of created beings sort of like this: 1) Angels and demons 2) Humans (except Jesus, who is the Incarnate in my tradition) 3) Animals and plants In my tradition angels and demons are similar in abilities; the main difference is the choice they made when God created them. Angels obey God, demons (or rebellious angels) disobey. Both have hierarchies. Humans are believed to have guardian angels guiding the soul toward goodness, while demons try to lead people away. Neither angels nor demons can know the inner thoughts like God, but both are much more capable than humans. For example, I’ve heard people say angels or demons could make very good guesses about future events or excel at chess. That’s why we might pray for people who commit murder, hoping they repent, but not for Satan or his followers - they knew the consequences of rebellion. Also, angels and demons seem to be aware of a person’s weaknesses. In exorcism stories, a possessed person may say things about sins others present haven’t confessed. The idea of jinn doesn’t exist in my Christian worldview. The closest analogs I’ve heard about are the nephilim (giant offspring of angels and humans) or the European concept of fairies. My questions are: 1) Why did Allah create jinn? What is their purpose and what can they do? Are they more like angels, demons, or something in between? 2) What does Islam teach about the nature, roles and abilities of angels and devils? 3) Can people see jinn, angels or devils? Have you ever seen one, and if so what should someone do? 4) Does Islam include the idea of guardian angels or of possession by devils/jinn? Jazakum Allah khayr for any clarifications - I’m asking sincerely and trying to understand from an Islamic point of view.