Anyone else having an issue on 07 Fresh Start Worlds where you are unable to login and your Jagex Launcher doesn't even work? But Runelite keeps telling you you need to download Jagex Launcher?
Based on what you've written, it sounds like this is the error you are getting:
This error indicates that the email and password you've entered are incorrect. If you are certain that you have entered the correct information into the login screen, you may want to double check the security of your RuneScape account.
While the Jagex Launcher will eventually be required to play RuneScape/Old School RuneScape, the only people it is currently mandatory for are those who are part of the Jagex Account Closed beta and have migrated their accounts over. For everyone else, you have the option to use the launcher or log in through the game client as normal.