The Humans of Pokemon Dynasty (PX3) also known as Earth Humans are not the same ones as everyone is familiar with from Pokemon World (PX2) also known as Poqmorian Humans.
Poqmorian Humans (PX2) were actually a pokemorph-only evolution of Primeape. Over time less and less Primeape have been evolving into Poqmorian Humans, speculation in the scientific community speculated that nature viewed the evolution into Poqmorian Human form as an evolutionary dead-end and over time the lack of evolutions to this form combined with time have conspired to remove this particular line from existence.
Earth Humans or effectively humans as we know them have been found on the planet earth. Earth Humans are born as humans and never evolve. They lack much in the way of martial abilities that Poqmorian Humans do but they do have one feature about them that does make them desirable to conquer in a friendly manner. Humans are breeding compatible with most if not all pokemorphs and pokemon.