All languages change, even languages you don’t speak or know about! I think we get used to the idea that our own language changes since we use it all the time and you can see the changes happening. But we are uncomfortable with another language changing. Kinda of like trying to hit a moving target. How are we supposed to learn a language if it keeps changing!
But learning the history of language is still very interesting. Languages change for many reasons. It could be because of political forces, social forces, or internal linguistic forces such as the break down of a case system, like what happened in English. In Swedish’s case, “de” and “dem” used to be distinguished, but are no longer. For more detail, check out the video in this post.