Ok, so warning you now, I can make this go on FOREVER, I will try to not get off topic!! XD I am starting with one that I feel is the least likely to happen. This all involves, fantasy animals, so yes this could count as a TGH or ROTR theory, but at the same time, it can include unicorns and dragons, and all of that stuff!! XD onto the theory!! XD
So one of I want to say was my BIGGEST childhood belief, was the fact that there was more than one time period on this earth going on at the same time, and they all included different animals. So the thought of their being more than one time period, or even look on the same planet, was a big thing for me, which could also include different islands. The ideas are honestly endless, there could be so many different things, and you would never know it, what if it was a time period before the dinosaurs, or after all the humans are gone, what would roam the earth at those time periods is what really got me thinking about this.
I mean think about it, there could be horses in the SKY at those times, and we would NEVER know it because it is at a different time period, in a different realm. I mean I could dig deep into this and even tell you straight up facts about a mystery, so just sit back, and read cause this could go on forever!! XD.
So there has been one case that is known. It was a dude named:(Nvm I couldn't find the actual thing, but it is real...-_-) but basically, he was trying to get on a plan, and it was set for an unknown city, and so when they put him in a prison like thing, and it has high security. but then randomly, out of NOwhere, he just straight up disappears, he wasn't caught walking out of the building, so where did he go? I believe that this shows the idea of different things going on in one place, but never at the same time, that our past replays on it own, and we go through the future as ourselves, but our future self also does the same thing.