Real languages change over time. There’s no such thing as a language that’s the same today as it was a thousand years ago. Things change in conlangs, too. In The Lord of the Rings, Tolkien charted out ancient and newer versions of Elvish.
The first Elvish word for people was kwendi. But in the language of one of the groups that moved away (the Teleri), over time, kwendi became pendi. Among the Avari, who spread throughout Middle Earth, kwendi became kindi when the w dropped out.
From the TED-Ed Lesson Are Elvish, Klingon, Dothraki and Na’vi real languages? - John McWhorter
Animation by Enjoyanimation