Neat game! It'd help to have a visual indicator for what weapon you have equipped/how you can equip them, especially since the keybindings of 1, 2, 3 are a bit awkward for weapon equipment.
Aside from that some visual feedback on when you hit zombos would be nice.
Also something to keep in mind going forward is that the UI won't always scale on other people's computers, and as a result it ended up being really tiny for me! You can look into Unity's canvas system if you want to learn how to fix that going forward!