Why do you suppose they chose the Inhumans to lead into Avengers: Infinity War part 2? Not really familiar with them. Do they play a fairly pivotal role in the comics?
Traditionally Inhumans have had a closer relationship to the Fantastic Four. Inhumans are a race of humans who were genetically altered by the Kree. The Kree we briefly saw during GOTG. The villain Ronan was a Kree. Traditionally the Kree are in a prolonged conflict with the Skurll. However since Marvel does not own the rights to either the FF and their villains (Dr. Doom, Galactus, Silver Surfer and presumably the Skrull) we probably won't get a reference to the Skrull in the MCU. The Inhumans like mutants for the X-Men franchise all have special abilities that separate them from normal humans.
Notable ones would be
Kamala Kahn: Shapeshifting
Black Bolt: Super Strength and extremely powerful sonic voice
Medusa: long hair that is as tough as steel that she can control.
Lockjaw: Dog creature with teleportation powers.
Crystal: Element Manipulation.