In terms of what the World of Warcraft Classic Best Classes are, Warrior and Priest stand out almost instantly. This is partly due to the fact that Protection Warrior is the only viable Tank Class in WoW Vanilla Patch 1.12. Both the Proc Warrior and Priest are required for Raids and when combined in a PVP setting can be a fierce combo on the battlegrounds.
Balance: Moonkin Aura - Starsurge grants 4% spell critical strike chance to 8 allies within 40 yards for 18 sec, stacking up to 3 times. Feral: Leader of the Pack - While in Cat Form, you increase the melee and ranged critical chance of raid members within 40 yards by 5%. Leader of the Pack also causes affected targets to heal themselves for 4% of their maximum health when they critically hit with a melee or ranged attack. The healing effect cannot occur more than once every 6 sec. Guardian: Sharpened Claws - Maul increases the damage done by your Swipe and Thrash by 25% for 6 sec. Restoration: Overgrowth - Instantly applies Lifebloom, Rejuvenation, Wild Growth, and Regrowth's heal over time effect to the target. Hunter
My general (unfounded) suspicion is that mob damage tables are mostly correct, but there is some sort of mitigation/damage reduction occurring that has yet to be explained. The only way the tiger could do regular damage to a higher armour Tips and 1-3 damage to joana is if there is some mitigation occurring for joana and not tips, or if they are on different shards/layers and for some reason the stats are different between the layers (extremely unlikely/impossible), or the tiger in the joana clip just happens to be born with a disability. But I should probably leave the baseless conjecture to the experts.
The quickest way to level up is to travel through the game's zones, completing all the quests you encounter along the way. Completing quests grants you Experience points, which will slowly fill in your experience bar with blue or purple. When the bar fills, you reach the next level. Alternatively, you could choose to run Dungeons or Battlegrounds, which are not covered in this beginner's guide.