Ok, we can scale back all works of fantasy and find a common theme... every story has already been written before, we know that... but its the variation on the classic theme that makes it interesting.
So we see the classic theme going, happy to start, bad guys come, fight, blows up the world, now we rebuild. I can see how the game mechanics are writing the story, which is a fine approach to take.
I see the components of ideas coming together...but don't be afraid to go deeper here in the lore. If you want a strong race that is interesting, you have to take it farther. Good character design typically is excessively exaggerated from anything you would encounter in reality. People love minsk in baldurs gate, but in fact the guy was a raving loon who would have been locked up in a padded room, most likely if we ran into minsk in real life we would cross to the other side of the street and avoid him, but for whatever reason we love him to death in the game.
For example, lets take a look at the human characters. I can see here you guys had an idea for the + stat bonuses the race would get and then decided to build a character around it (the diplomats) (the merchants) etc. Don't forget about the other way. Dwarf fort has an interesting design philosophy in that they write a story, then jot down things that they would like from the story to happen in the game, so as you examine these races deeper it might give you ideas for unique units and even different mechanics.
So go deeper. What are the effects of the cataclysm on the human races? What was the order of things before the cataclysm, do old hostilities return... was there one civ that stood above the others but now is low, for example make the Tarth were actually ancient rulers and are prideful but universally disgusted now ,but the arrogance has never left them.
What about these crystals, all their power put there. What if there was a race that was predominately full of magicians who lost their power, and now stare at their former glory contained in a small shell, there it all is, untouchable to them. This could actually be your 'scientific, low magic' race, so determined are they to obtain their power. Think of how frustrated they would be... ITS RIGHT THERE, but they can't touch it.
What if people start worshiping the crystals? It was the magic of the world, are they not god like? Maybe there is a cult of the crystal surrounding every untapped crystal node and they have to be dealt with like a bunch of tree huggers by the logging company?
So what I'm saying is there is a very generic background lore here, but start thinking about it, how you would react if you were each one of these people surviving the generic death events, and then you get creative. The creativity of your interpretation of the generic events is where you will find the depth you want, I think.
