roughly under the tutorial mushroom town there should be some ruins of mostly white blocks, one of them has the basic offensive spell i think and another one has an armor

Really, just explore. I've found at least a couple really good spells by just walking around, and magic is (rightly) powerful, so they can't really just hand 'em to you.

My friend had that issue playing a full mage. If you need the starting spell
The first damaging spell is -->> in a chest locked inside a small ruin atop a plateau, within the mushroom forest located under Pwyll village.

There's a fair few spells in the game of varying types, but some are really hidden. I'm basically at endgame and I've been fairly thorough, so I do think I've found most of what's there.

I'd categorize them somewhat like this.

Direct Combat - just deals damage, these include:

Cipher Spear
Ethereal Flechette
Immolation Incantation

Combat Aid - these help mainly in combat but aren't directly damaging, this has:

Entice
Summon Skeleton (Normal, Archer, Wizard, Guard)
Slow
Spectral Shield

General Aid - these would help outside of combat (though could still have combat applications)

Reknit Flesh
Fade
Dispel
Agility's Addendum

Quality of Life - make things more convenient

Return Home
Emergency Airship Reembarkation
Advance Time

Oh, just as a tip, Return Home is really useful if you want to avoid a death by falling.