Driving with cruise control on and sudden jerking followed up by engine dying, engine wont start now.

Hey everyone, I drive a 2008 Subaru Impreza automatic. Car has had two owners and been pretty much babied it's whole life. It had it's 100k maint (head gaskets, water pump, timing belt) done a year ago, oil has been changed at 3000 miles religiously, I changed it 3 weeks ago. Ran into this issue yesterday.

My wife and I were driving with cruise control on set to \~ 62mph, we were steady for about 5 miles, doing some standard highway driving, and then started going down hill on a small slope and rpms were going up to utilize engine breaking(?) and shortly after going downhill we plateau'd to no slope up or down and the rpms were dropping as the engine breaking wasn't needed. At this time there were some serious jerk motions and sounds that happened, I turned off cruise control and was then coasting, started steering towards the roadside assistance lane and at this point I noticed the accelerator was not working, but I came to a full stop and put the car in park and since I had come to a complete stop and shifted into park all the lights in my dash were on (battery, red oil symbol, check engine, at oil temp, traction control, AWD, sport mode) . I took a picture of my dash, turned the key into the off position, waited about two minutes after composing myself, tried starting the car, it started successfully, all the dash lights that were present a minute ago were cleared, the car went into drive fine and the accelerator worked and allowed us to drive the remaining 1.5 miles home.

I popped the hood and looked for any immediate signs of damage but couldn't find anything that stood out.

My questions are:

1. What the heck just happened? Is this what you'd call popping out of gear or the transmission slipping? 2. Is it likely that any major damage was done to the car as a result of this mishap? 3. Is this an isolated incident that was a result of me letting the car try and figure out the gears on its own? My car is not known for their automatic transmissions, sometimes if I'm driving completely normally and have to make a turn, sometimes the transmission shifts and hunts for gears for a few seconds at a time just because it's having an identity crisis of the driving conditions.

Any advice is welcome and appreciated, please and thank you!

edit: When I got home, I started the car and then turned it off and restarted it three times to confirm it was working, which left me feeling confident. Came back about an hour later to move parking spots, the car started, shifted into drive and then it immediately died, and the light process repeated itself. Now the car will no longer start. It cranks, but never turns over.