Great Start. I imagine that after a bigger world and more content is added, this would feel a lot like slime rancher. I like the combination of a bright colorful world and FPS controls which are almost always relegated to grim-dark games.
As I'm sure you already know there are some technical issues with the build, but that's how jams go. Game mechanic wise I think the only really unique aspect is that the buffs respawn from plants periodically, so I'm assuming that that's the connection to the theme. "A bountiful harvest of health and bullets" interesting take.
Well done!!