Ever since you were born the world is constantly changing, not just through big events but in smaller ways too.
Not only that. You no longer exist. As you were at birth, that is. And after some amount of time every so often in your life, you will continue to be unrecognizable to the version of you from x years in the past. Your cells die off and new cells are created until you are literally composed of different matter than you once were. The closest thing to a constant thing tying you together would be the electrical signals in your brain. Memories. Like computer code sent from one PC to another. Also the DNA determining how your body is built.
It’s the classic Ship of Thesseus problem. If you replace a ship’s parts one piece at a time over many years until the old parts of the ship no longer remain, is it still the same ship? And in the same way, are you still the same you? Maybe our lives are full of many different people tied together only by our thoughts, memories, and genetic code.
The neurons you’re born with stay with you for the most part. Most of their complex organization is formed through a series of one time events early in development that can’t really be replicated and then stays with you for the rest of your life. You get shingles when you’re older because the same neurons were with you that got infected by chicken pox when you were younger are still there. There’s a few limited areas in the nervous system where new neurons might be formed, but in general neurons are life long cells so be nice to your nervous system. Most other cell types in your body are turning over as you said, including glia and other types of cells in your brain.
In the UK we call this the “Trigger’s broom” problem: https://www.youtube.com/watch?v=56yN2zHtofM
