Unless the idea that our brains are more like a radio, or television set, or something similar, is right - the actual you is your soul but that you exists outside of your physical body. Your physical body on the other hand is more like a drone, or sort of avatar, it only connects your soul to the material plane, and your personality here is affected by how much of the real you can come through, so if, say, your brain is damaged after that only parts do. Like, if there is something wrong with your television set the picture or the sound is no longer quite what is being transmitted. But all that goes the other way is permanently stored in your soul. So, if you lose your memory here that just mean that you no longer are getting everything through this way, but after your death you will have all of your memories, and everything that happened to you while you were functioning through your avatar body.

Which, I suppose, might fit the many worlds and many timelines idea and the ability to move from one to another in some way.

However, since our physical bodies will be worn out sooner or later, even if the kind of "jumping" from timeline to timeline was possible, sooner or later you will run out of timelines where you have a working avatar body because all of those got too old to function anymore.

Unless the idea that our brains are more like a radio, or television set, or something similar, is right - the actual you is your soul but that you exists outside of your physical body. Your physical body on the other hand is more like a drone, or sort of avatar, it only connects your soul to the material plane, and your personality here is affected by how much of the real you can come through, so if, say, your brain is damaged after that only parts do. Like, if there is something wrong with your television set the picture or the sound is no longer quite what is being transmitted. But all that goes the other way is permanently stored in your soul. So, if you lose your memory here that just mean that you no longer are getting everything through this way, but after your death you will have all of your memories, and everything that happened to you while you were functioning through your avatar body.