Thanks for your feedback!:)
I don't think an AI would work as a fun experience for this type of sandbox death match, but we are aware that most people will not be able to try the game with another person, which is a shame, but we are planning on making it playable against opponents online :)
Regarding the arrow selection, you should be able to select a new arrow by pressing S or DOWN when the arrow-selection box is spinning over your head!