I have 5 hearts and 9 defense from my armor. My strongest weapon has 20 damage. I noticed I'm too unequipped for most stuff. I get 1 shot by any miniboss and boss bokos.
I don't have much of the map. Only the first tower and a tiny bit of depths. Any advice? Where can I get decent early-mid game loot?
Something I didn't realize till recently, but there is a game mechanic that doesn't let you get one shotted at full hearts. Keep cheap food and top off every hit. I found that easier to do and build stamina until I could get better weapon fuses, armor, and enough hearts to not get 2 shotted.
Muddlebuds are fun, but Puffshrooms are godlike! Especially if you can get an Eightfold Blade. Sneak attack everything.
One of my favorite techniques is to Puffshroom a monster camp in the depths, grab all of the ore and run away, using another Puffshroom on the way out if needed. This lets you get a lot of ore without wearing down your weapons or wasting time fighting the same old Bokoblins and Moblins.
You can trade it for two things: Zonai Charges and Crystalized Charges. Zonai Charges are used in vending machines and to recharge your Energy Cell (personal battery) when you just need a little more juice to fly somewhere. Crystalized Charges are used to *upgrade * your Energy Cell so it lasts longer, but you do find a ton in the Depth in chests.
When using Autobuild, you don't actually need to have the required parts. Autobuild will manufacture the parts you need for 3 Zonaite each. In my opinion, that's the most important use for Zonaite Ore. At one point I had like 600 Zonaite Ore (regular size), and I actually ran out because I was using it so much for Autobuild.
You will have little use for it early game. It's very useful later on (mid to end). Not sure what to say about it as you've said you don't want any spoilers