In a fantasy world, which has both medieval and early-modern inclinations (300's - 1690's), and factors such as magic (though very rarely used directly offensive, so there's no things such as 'fireball' and et cetera) and many beasts like dragons, basilisks, orcs and vampires; How thick would horse and human armor be?
I thought of something close to 3.5 mm or 4.5 mm (with padding), enough to stop a shot at close range (considering that black powder is being used), light enough to be carried around with ease, and thick enough to protect the user against most inhuman threats, but I feel this isn't enough, mostly because I am no expert on this subject, so I'd like to know which would be the ideal armor thickness for
A - A common healthy soldier, a little stronger than the average man.
B - An elite warrior, very strong, very experienced, very well-trained and equipped, and with a grain of "inhuman" aspects, such as enhanced reflexes and stamina, though not unnaturally strong.
C - A "Beast-hunter", an expert warrior who's job is hunting beasts, such as the already mentioned dragons. It should be also mentioned that these beasts aren't much bigger than say, an elephant, and some of them are really intelligent, but none can compare to a human. (Not yet, but that's a long story)
Projectiles and weapons in question - The weapons typically seen on the battlefield would be poleaxes, pikes, shields, muskets, arquebuses, longbows, maces, warhammers, longswords, lances and blunderbusses.
The "weapons" used by beasts will more often than not be claws, not terribly sharp, but very long, sharp teeth, powered by large powerful jaws, and sometimes as beasts will also make use of fire (not hot enough to melt armor though, and not used long enough to cook the hunter inside his armor) and poison.
Magic won't be much of a worry here, in part because it's use in warfare is not wide, and the nature of magic is very erratic, each wizard has a "type" of magic different from the other, so unless armies forge armors specifically made to fight an individual wizard, anti-magic armor won't be seen very soon. As a side note, usually spells and magics powerful enough to harm or kill a man can be held at bay by common armor.
The materials used to forge armor that I thought about were good ol' layered steel, but if anyone thinks of a better material, that's available in the 17th century of course, please tell me.