Even while Scorn gives you a weapon to defend yourself, killing enemies still leaves you more vulnerable.
Pressing "E" will heal you in Scorn, but you won't be able to do so until you've activated the glowing red pods in the second alien structure you see on your quest.
Approach the pod up ahead after inserting the key into the pod interface. To get the bulbous mound of flesh with tentacles sticking out of it, use the console to its immediate left. Surprise! It's a tool for your healing.
Wait, the tool is empty, so in order to use it, you need to find yourself what amounts to a blood bank. These are typically hidden away in remote, dark corners.
They’re rare and single-use only, so do explore and don’t miss even one. One blood bank provides around 3-4 charges, for a maximum of 8 charges.
Check the number of charges you have by aiming with your weapon or opening your inventory, Represented as nodes above your health bar.
Now you can heal in Scorn, you should be able to survive almost everything in the game.