Monster were confident in their physical strength and body.
And unlike human beings they were attuned and much more compatible with elemental energy.
That is why human seldomly fight monsters in the same rank or level as them as they were in a disadvantage.
Other than human geniuses common practitioners could only fight Normal Grade to Good Grade monsters in a one on one fight and they would still have a difficult time.
Monsters would become much more intelligent as tbeir grades rise but this in turn decrease the possibility or the speed of their reproduction.
Take the dragons for example they give birth in either a hundred or a thousand year at least.
This is the reason why Shadowslash was so shocked upon seeing LS and Shiroi.
As long as both his clones cultivate properly with just their innate talent in just a couple of years they would also stand besides the strongest people in this continent.