Hello everyone,

Recently started a new multiplayer game with my friend.
I decided to try out the Aasimar race, and we thought it was OK for me to level up a bit slower than him.
However after discovering that I will also incur a 20% XP penalty for multiclassing I really would rather like to make a new character as a Human, or else our level difference will just become unfun.

I have made a new Human character in the same level as my Aasimar character, my question is can I somehow import it into our game so we don't lose progress or do we have to start all over?

You can. When you set up the game, you can set it to use local characters only or not. I'm not super familiar with nwn2 mp, but if it's like nwn1 then you can also give the character file to the host and they can find a folder with your login handle inside a folder with the game name and drop the character in there.