@SenjiQ it's just that there is no direct line for the entire family. The women seem practical enough to keep the royal family going. Even if the men are lothe to have children of their own.
We have not been told how old the orc is; we (and all the perceptive objects) are left to assume that he is a shota by inference; the same with the Loli. Each chapter starts with the hero's (or the demon king's) age at the begining of the chapter.
@beepboop1 I imagine 2 reasons for the moon;
1) power consumption; to transport all of those people and materials will take large amounts of power; to get to mars may have taken more power than available to them 10 years ago.
2) observation of what the humans are doing; on mars the witches...