There were multiple sources from which people in this world were able to gain levels, and Evelyn was well aware of most of them.
The first one was a passive acquisition of energy that naturally flowed into their bodies with time. This meant that the older someone was, the more experience they would acquire simply by existing. This was how most non-cultivators gained their levels, and it was how most people who leveled up before they even acquired their cultivation technique got their 'experience' or 'energy'.
Of course, this 'passive trickle' also varied from person to person. A human with a regular body would have a much lower rate of acquiring experience like this naturally than someone with a spirit physique. This was why most of the commoner children that Evelyn had encountered on her way to the ancient academy were still level one.
