Just started playing and something seems wrong. Casting Charged Bolt costs no mana and everything dies in 1 hit from my staff. I do take damage if something hits me, but it rarely does. What's up with that?

That sounds mostly normal for an early start. If you're casting Charged Bolt from your starting staff, then it costs you staff charges, not mana. You can pay the witch to recharge your staff, or you can irreversibly degrade its maximum charges by recharging it yourself. I strongly recommend letting the witch handle it. Your quick cast icon in the bottom right will be orange if you are casting from a staff, red for a scroll, and blue if you are casting from mana.

Early game monsters have poor to-hit, so that you don't get overwhelmed as a new player. Don't get complacent. It gets more dangerous soon. Early monsters also have fairly low maximum health, though if you're getting a one-hit kill on everything, that does seem a bit off. What is your displayed damage range? What types of enemies are you comparing against?