My dad is left handed and I got used to using the mouse with my left hand too as a kid.
I use IJKL for moving in every game and rebind keys around those for everything else.
Got my shield on 6, main weapon on 7 and bow on 8 because those are reachable well.
1-5 are tools which don't require to be pulled quickly.

Honestly, try to get away from arrow keys.
There isn't enough stuff around to rebind important controls to in almost every game.