OK, I'm going to come in from another angle. I'm a tabletop roleplayer, and a GM, and curious. That means I have seen my fair share of RPG systems.
Most RPGs have primary stats, but what's interesting is that the primary stats change according to what kind of story you and your players want to play.
Dungeon and Dragons has the classic (duh, it's the original) spread of Strength, Dexterity, Constitution (physical stats), Intelligence, Wisdom, Charisma (mental stats). It generates campaigns that are relatively balanced between brain and brawn.
World of Darkness has 9 base stats. 3 for physical (the same Str, Dex, Con as D&D), 3 for mental, 3 for social. Each domain has a stat about power (Str for physical), a stat about control (Dex for physical) and a stat about resistance (Con for physical). Dividing the mental stats into pure mental and social stats leads to campaigns that are more focused on the social aspects.
You can find different spreads in different game systems, the point of what I am trying to say is that how you build the stat blocks of a character influences what direction you expect campaigns (and, in your case, LitRPG stories) to take place.
You can have an infinity of stats and splats (archetypes, like race or class) on a character sheet, what will really matter are those you actually use. If you want your story to focus on physical stats, break down the physical stats of D&D into more stats: Agility for movement, Dexterity for fine control, Resistance and Vitality instead of Constitution, you can even get further if you wish.
The real question is: how does that system serve my story? If it's important that your heroes can do different physical things, then a grouping of Brawn will be bad for your story. If your heroes are schemers and intellectuals, getting a single Mind stat is also ill-advised.
Unless you want to go the "let's abuse the system" road, which can also be fun: "in a system that has a single physical stat, everyone is one version or another of a mage, except that weirdo who maxed their physical ability and kicks everyone ass with it" is a fun premise.
Now that we've dealt with primary stats, let's move on to the other parts of your character sheet: secondary stats, levels and skills. LitRPGs have a different balance to those than tabletop RPGs, but I'm going to speak about the latter.
Secondary stats are derived from the primary stats, either directly (ex: Initiative is Dexterity+Perception), or with the addition of something else (ex: Health is (Constitution+a modifier that depends on class) X level).
Things like health, mana, ki, stamina are very often secondary stats. Those generate a pool of ressources that can be depleted and refilled. The other type of secondary stats are static stats like initiative, attack bonus, defense, save throws. Those give a specific bonus to an action and are closer to skills.
Again, what secondary stats you include, if you include them at all, and the way to calculate them are up to you and the kind of story you want to tell. A LitRPG story about a mage without a mana stat is completely doable, but you'll need another way to limit their power or you'll get a Mary-Sue.
Skills are the biggest difference between LitRPGs and tabletop RPGs. In LitRPGs, skills are often independent from any stat, except maybe as a prerequisite. In RPGs, a skill level is the sum of the skill rank and the relevant statistic bonus.
What skills you include, how you obtain them and the power they bestow also depends on the type of story you want to tell. Do you have Diplomacy, Small Talk, Streetwise, Carousing, Deception and Bargaining as skills or do you group them under Social? Or do you have some of them but not the others?
Levels, finally, are there to help you improve all of the rest and possibly grant you other powers. Not all tabletop RPGs have levels, and those that do generally have lower levels in total than LitRPGs. A level 20 D&D character is almost a demigod, a level 20 LitRPG character is often just a beginner.
You need to think beforehand about the range of everything: what is the normal stat value of the untrained human? What is the maximum value of it? Is it easy to raise your base stats or hard? What does it imply for your secondary stats? Same thing with skills, levels and powers...
And, again, but that's really important: what do these choices mean for the story I want to tell?
I hope I have given you food for your story and not confused you too much!
