Since Marvel couldn't release an X-Men movie until Disney bought Fox, they tried to set up Inhumans as a replacement for mutants. The resemblances aren't accidental.

You can also become an Inhuman at any age due to the ancestry involved there compared to mutants where it is specifically around the time of puberty in most cases.

Apparently Marvel was doing a big Inhumans push in the comics to distance themselves fom the X-Men. Their similar in both universes (that’s why they made Ms. Marvel a mutant, now the X-Men can be used they’ll rather do that than X-Men knockoffs).

Inhumans were hardly knockoffs. They were around for decades. Yes, they gained more prevelance due to this move against Fox, but they hardly were just the replacement X-Men before.

Inhumans are an entirely different genus (Inhomo supremis), Mutants belong to the same genus as humans but a different species (Homo superior).

But yes, Inhumans can't naturally develop their powers, they must go through Terragenesis.

Marvel couldn't use mutants, so they used the Inhumans as a way to show the incredible hate for enhanced people (specifically the Inhumans species). I like that there bringing mutant fear and hate into the MCU on a much larger scale than AOS and Inhumans ever did.