You copied backup files over and since those end with .old your dedicated server probably created a new world because it couldn't find the required .db and .fwl files.

The path you posted also looks wrong. The files should be in:

%userprofile%\AppData\LocalLow\IronGate\Valheim

and there either in \worlds or (the new folder) \worlds_local

unless Iron Gate changed that too. But that's where my dedicated server has the world file.

In the path you posted I have only one of four singleplayer worlds and it is the only one which was uploaded to the Steam cloud yet.

Either way you have to copy the Ourservername.db and Ourservername.fwl files.