Uchiha Brahman wasn't an option. In the entire Empire, only Uchiha Brahman was a Brahman. He stood above all!
Kshatriya, Vaishya, and Shudra.
Kshatriya.
This class had nothing to do with one's abilities and everything to do with one's genes. As everyone knew, chakra was a supernatural power formed by combining spiritual and physical energy. In theory, it had no limits.
A person's strength and chakra reserves, then, naturally had a lot to do with their body and genes.
Kshatriya were Empire citizens who, under natural conditions and without any modifications, could obtain more than a jōnin-level amount of chakra purely through their genes.
Although the Shinobi World had terms like Kage, jōnin, Chunin, and Genin, when Uchiha Brahman was monitoring the entire planet, he had recorded the physical conditions of every observable ninja whenever he had nothing better to do and analyzed the data. Now, these terms like Kage, jōnin, and Chunin were no longer just labels; they had become genuine rankings.
Next came the Vaishya.
Vaishya were Empire citizens whose chakra reserves, at their natural peak, reached the level of a Chunin or Genin.
Finally, there were the Shudra.
They were Empire citizens who, under natural conditions, could refine only a small amount of chakra.
What if someone couldn't refine chakra at all?
Sorry, but almost every living thing in the Shinobi World could refine chakra. Even a dog by the roadside could do it, as long as it knew the Chakra Refining Technique.
This was a large-scale genetic selection process. By sorting people this way, they could identify the strongest organisms under natural conditions and have them reproduce, making the human race stronger. And the stronger these humans became, the more power they could provide Uchiha Brahman.
It was just like collecting taxes: the more money people