I use a wacom graphic tablet, i.e. the kind that you use to draw on with a pen(but not the ones that work as a screen)
These things allow me to almost instantly move the cursor to a point on the screen where i want it to. Thus it was incredible easy for me to just point at a Zombie and instantly knew the target would hit it. (I personally think a graphic tablet is better for navigating on a computer screen than a mouse. The only times where it is not better is in first person shooter games. Of course, it's a tad too expensive for non-artist to buy such a thing for just navigating the cursor :)
Wait, you can run or crouch in the game? Here is another advice i would love to give 90% of all itch.io developers: Have instructions of how the game works IN the game(especially in the first few levels as a quick tutorial). Not just in the description. Of course with GameJams it would mean spending time on something that isn't absolutely necessary, but if you have the time, do it.
Yeah, enemy character following the player is already AI. A very basic one, but it's still AI. AI in videogames just means that an enemy character doesn't move in a fixed pattern, but instead moves according to how the player(or environment/NPCs/other enemies) behaves. Thus if the player moves left, and the enemy then also goes left after him, that is an AI.