Thanks for playing the game! Some things that might help:
During battle, if there are multiple possible targets, you can cycle through targets with the mouse wheel or Page Up/Down or R/T or L/R on a gamepad.
To see if spells, items and attacks are possible to use on a target during battle, there are four icons next to the target list (top left-ish) that show if attacks, item use or spells are possible on the current target.
There's a How To Play button in the menu, but things are explained more conceptually there.
Thanks for the feedback. My next RPG project adresses many of the criticisms regarding the interface.
The game will get a bit harder around hour three or so. I wanted it to have a soft start.