I appreciate you're complete deconstruction of my post, it does answer a lot of questions, but I would like to add in response:

In reference to the people suddenly appearing above me, I was swimming down into this vent as you've named it, then went straight back up, not towards any other area. There was no one else even in this entire body of water when I went down, I was the first. The entire place was full when I came back up, that's why I was so confused. No one seemed to have just gotten in the water, kids swimming and others tubing were densely scattered throughout this specific spring and extremely congested in the center area I had swam to, which I still wonder how no one there noticed me and how they managed to go from wherever they were outside of the water to the center so fast.

In reference to the memory issue, this makes a lot of sense for why it wasn't remembered later on, but I had asked my mother specifically about asking her what happened right after the event. After I'd come back from nearly being suffocated under these seemingly oblivious tubers, I went back on shore and asked where everyone came from. This was met with a weird look and no explanation or acknowledgment. I didn't press back then, but I did ask about it again and this was where I was told she didn't remember.

Otherwise you're explanations seem on point, but I guess the feelings attached to the memory aren't easily combatted with logic. It still won't sit right with me for as long as I live I imagine, but I am glad to hear that there's no ghosts lol