[@UltraCraftGames]
A singing character would be perfectly fine, so long as he can handle some tough critics here and there...

Skills are things that the players can learn simply by discovering them and then practicing. If you read a magic book and learn to cast a spell, then practice with that spell on different targets or do experiments with it, that spell will increase in power. Kind of like Skyrim, but grinding Iron Daggers wouldn’t work so well after the first few times. Some skills may also be passive traits. 

For the skills currently listed:
Physical Damage Resistance causes you to take less damage from attacks. If you have this skill, a sword can’t cut you as deep or a hammer won’t break your bones so badly. You aren’t invincible, but you take less damage. 

Beast Senses causes you to have sharper eyesight, better hearing and smelling, and in general be more sensitive to your surroundings. It’s not nightvision or danger sense, but it’s like comparing a dog or cat’s senses to a human. 

Mana Orb is a simple blast of magic. At the beginning it would only do as much damage as a strong punch on average, unless the enemy is weak to magic. As it gets stronger it becomes a generic, non elemental energy blast. 

Lesser Force is like telekinesis, but only at arm’s length, and it isn’t very strong. A Wisp could use it to pick up food, but not to throw a heavy rock, for example. 

Levitation allows the user to float about three feet off the ground continuously. To rise higher requires effort equivalent to physical climbing, and the Speed is never faster than a brisk walk. Think like Navi in Zelda. 

Use Light Equipment is very simple. You can effectively pick up and learn to use light weight weapons and tools. These things usually require multiple fingers and opposable thumbs, which is why Goblins can do it right off the bat. 

Stun Fang injects poison when biting an enemy that will cause their bodies to seize up. They become unable to move until they are cured or it wears off. 

Poison Spit lobs a ball of liquid poison over a short distance. Even if it doesn’t inflict status, it has an acidic burn. 

Minor Heal only heals a little bit of damage at a time. It helps with nasty scrapes, cuts, and bruises, but couldn’t do much for a broken bone or a deep tissue laceration. 

Lesser Flight means the user can fly, but not for long distances or at great speeds. Comparable to how everyone can run, but not everyone can run for a mile without stopping or sprint 100 meters in 10 seconds. 

Shield creates a barrier of magic around the target, protecting them to a degree from any damage. Strong attacks will still chip through or even break the shield entirely. 

[@King Cosmos]
The entire bestiary is based on the usual JRPG and D&D monsters, so whatever would be upper tier there is likely so here. Dragons, Archdevils, Liches, etc. Dont worry about trying to find the “most optimal” build or path, though. A dragon who never practices their fire breath might end up being weaker than another lower ranked monster that puts all their effort into training their own fire magic. It depends on your actions, not just your species. 

I have a large number of monsters planned out, but there’s always a chance I missed something or your idea may turn out to be better than mine. Feel free to offer whatever suggestions you would like, just be aware if they get shot down it doesn’t necessarily mean they’re bad ideas. 

[@Gobby]
You are pretty much correct. For example, a Goblin might turn into a Hobgoblin, learn some magic from a book while still being a jack of all trades, then become an Orc and take up the role of a shaman. Another Goblin might become a Bugbear, which is more focused on physical power, and then an Orc with a berserker role in the group. These two Orcs might look very different and would of course have different skills and personalities, even though they’re still both recognizable as Orcs.