That's very fair, I did something similar, "hey, I want to see if this mechanic has potential".
In this case, it for sure has. Combining movement and actions is really satisfying, consider adding an "up" or "down" mechanic for each class, perhaps selectable abilities, maybe the ability to strategise around enemies, and you've got a full, innovative game!
The only change I might make would be to have an "absolute" key, like Q for the defender and W for attacker, wherever they are. Or perhaps a "tab" key, where you select the next fighter