Cultivator

Cultivators are hard-working (Or not-so-hard working) Individuals who actively pull in the essence of the heavens and the earth. They are categorized in ranks, and the power in between ranks exponentially increases, by which I mean it would take ten F-Rank 1 people to beat a single D-Rank 1 Cultivator.

The G-Ranks
The G-Rank is the rank below the low, so low that basically only Newborns are at it. The average child human would probably break out of the G-ranks at 2 or 3 years old. This rank is almost explicitly reserved for inanimate objects(thus newborns).

The F-Ranks
The F-ranks is around where the average human is at. As said previously, the average Human probably breaks into the F-ranks at around 2 to 3 years old, and throughout their life would make it to about F-rank 6

The D-Ranks
And we are now in the ranks you cannot obtain accidentally, as to get to the D-ranks you need to break your cultivation spiral into a fractal. It is not gone into too much what this entails, but from what is mentioned in the books, It envolves making your chi spiral into a bunch of different chi spirals that are all also 1 chi spiral (Are you confused yet?). You can be forced into the D-ranks, but it is a brutal process that takes days to finish and is best done in a locked room with bathrooms for observers.

The C-Ranks
The C-ranks. Not much is known about how to get there, except for the Idea that when you get to the C-ranks your cultivation spiral becomes solid. The current best guess is that this means that to get rid of the cultivation technique you are currently using would kill you. During the C-ranks, you are supposed to build your aura in preparation for the B-ranks.