When I made AI for the first time (of two at the moment), I didnt make a thinking one. I just put up a variable that I randomized, and if the numbers was inbetween a cirtain spektrum, it would do one thing, like follow, or hide. If the player passed bellow it (you couldnt even mive in 2d, you could only move back and fourth across the screen, and an upper player would either be controld by the AI or by a fellow player), well, it fired. It was very basic (but still it was better then me
), but I hope it can inspire you. Goodluck.