Stats, the most basic part of an RPG, and a hard part to write in a fanfic while keeping it relevant, i will explain what they'll do, and what combination should they be bought in and possibly training regimes to use for them. You get 5 stat points per level to spend and can train to get them

STR. Strength, as the name suggest, makes you stronger, but that's not all, it also increases your hp and stamina (yang) regeneration (10 STR=1% HP recovery per minute + 1% SP per minute).

VIT, Vitality, increases raw hp, durability of the body and stamina (yang part of chakra).

DEX/AGI, Dexterity/Agility, increases movement, reaction speed and dexterity.

INT, intelligence, increases calculation and tough speed, memory capability and raw intelligence (yin part of chakra)

WIS, wisdom, increases decision making skill, charisma and MP (yin) regeneration (10 WIS=1% MP per minute)

LUC, luck, affects enemy drops, probability manipulation

HP, health points, base health points is 100, extra 10 HP per 1 VIT

SP, stamina points (yang), base stamina is 100, extra 10 SP per VIT

MP, mana points (yin), base mana is 100, extra 10 MP per INT

CHA, Chakra, base chakra is 100, extra per MP+SP

EXP, experience, is gotten through exercise, defeating enemies, studying and quests

These are all the stats, as you may have noticed, there were mentions of yin and yang, as chakra IS made out of yin and yang, this brings me to the first built:

Mage/ninjutsu specialist:

Points distribution: 2 into VIT, 2 into INT and 1 into WIS

Train in vitality through actions like jogging

You need to increase both VIT and INT to get more chakra, the amount depends on the MCs clan (or lack of), as any clan member should get a chakra ratio boost. (Exemple: Uzumaki bloodline: X10 chakra)

WARNING: non senjutsu based ninjutsu are ineffective against strongest characters

Swordsman/kenjutsu specialist:

3 into DEX

1 into VIT

1 into WIS

Should study for INT increases to be capable of using chakra to amplify a weapons effectiveness and train in dexterity, one point into WIS due to becoming exponentially hard to train later on.

Juggernaut/tajutsu:

4 into STR

1 into vitality

Vitality training for hp recovery increase is ideal.

Juggernaut/8 gates

4 into VIT

1 into STR

STR based training advised, VIT points needed for regeneration.

Genjutsu specialist:

3 into INT

2 into WIS

Studying and philosophical debates (lame as they may be) advised, genjutsu uses mostly MP, so WIT and STR is not absolutely needed.

WARNING: Strongest naruto characters are immune to genjutsu to an extent

Juggernaut/senjutsu:

2 into INT

2 into VIT

1 into luck

Senjutsu1s strength directly depends on the amount of chakra someone has, so a balanced INT and STR stats are needed, luck because let's be honest, you'll need it to survive and master senjutsu.