How or Who give names a meaning?

So, while trying to find a name for this baby on the way, I read a lot of baby sites and baby names of other children.
On one site, they were listing the name they were going to use for their unborn baby, and the meaning.
Well, someone had written “Caden- means fighter”
Instantly I found that odd, since I assumed Caden was a made up name as of semi recently. I had never heard it until I was pregnant with my son, only about three years ago.

But, it’s on the baby naming sites, with the origin as American
So, is anything “made up” going to be an origin from America? Most have origins from someplace else, so this is just confusing to me.
I’m also curious as to who gave the meaning “fighter” to the name Caden. How does that happen? And how do you find out how long a name has been in use? that one might be sort of hard.

oh, and before I get crap about my sons name, it IS a “real” name, and has an English meaning.