Existential Questions (English)

What if you died some time in the past, but you don't know, and the life you live now is a continuation of that previous life from which you carry many distorted memories?

What if that happens to everybody, and there is a multiverse of different lives, which start, end and interact with each other in a very complex way?

What if all you perceive with your senses is what reality is, and what you don't perceive dies and ressuscitates everytime you encounter and leave them? What if the opposite is true and you and everything you see is wearing off or dead till the moment someone sees or hears you and you think you're sharing the same existence but actually you are living in your own universe?

If a branch of a tree falls in the middle of a forest and nobody is there to listen to or see it, does it actually happen? Does that branch exist? If you are alone in a forest and nobody sees or hears you, do you exist?