I don’t think they are going to say anymore about monoliths origins, Maveth, or Hive.

Time travel, history of SHIELD, and the Chronicoms seem to be the focus of the finale season.

Until Inhumans are rebooted for sure, the Royal Family are on Hawaii. Aloha!

Kree connection to the monoliths; I think it was told in some season 4 episode. I do not remember which episode.

how the Kree made them; not entirely sure.

how Izel made them; she possessed Flint's body. Flint was/is an Inhuman. Inhumans are part Kree and part human.

Izel's connection to Hive; not sure if there was any. they for sure have similarities, but similarities do not necessarily mean an connection.

Royal Family; they and most of the citizens relocated to Earth in the last episode. where on Earth; the episode seems to not tell.

How I'm pretty sure they neglected to cover the Kree-Monolith connection. I think it's more likely the rogue Kree faction that came to Earth to create Inhumans found a black Monolith in South America upon landing by mistake while they hunted down humans to use and experimented on it, only managing to modify it to go to Maveth. Then again, they never explained how the 3 monoliths ended up in the Lighthouse base nor the how the first one ended up on the Iliad (i.e. the SHIELD missions that led to their acquisitions). Shrug.

correction:: the connection was told in season 2, not season 4. a Jiaying and Raina conversation.

this site's page for the "first" monolith tells that its creator was Kree.

Yes, in "Scars," Raina had a vision about the Monolith but didn't know what it was. She described it to Gordon who knew what it was. Jiaying said, "Only from stories passed down by our ancestors. It's Kree. Dangerous. Intended to destroy our people." Raina asked, "But didn't they make us?" Jiaying replies "Then they decided we were a mistake." Then Jiaying asks Gordon if he can locate it. Gordon then says, "If it's Kree, I suppose I can find a connection to tether."

Even then I'm kinda skeptical. Would the Kree admit to their 'creations' the Inhumans that their deadliest weapon wasn't really theirs? I don't think so. So the Inhumans passed on the lie to their ancestors without knowing it. I suppose aside from my theory above they modified an existing black Monolith, they could have found Izel's temple and used whatever hieroglyphics were around to try and make their own. As for Gordon's gift, you could argue that validates Kree made it but I'd counter his gift connects him to quantum energy fields of living beings and objects etc. so it being Kree or not doesn't matter. But yeah, the origin of the Iliad Monolith is something I hope the producers will be asked about.

as far as I recall, few races visited Earth in the distant past. Frost Giants, Asgard, Kree, and 2 Cronicoms.

Frost Giant's motive seemed to be to freeze the Earth; Asgard came to stop them. not sure if either of them were able to create monoliths.

the 2 Cronicoms seemed to only observe events.

so unless the upcoming movies/shows reveal others, Kree would be the only possibly on who created the monoliths.

edit:: about the monoliths at the lighthouse, some season 6 scene seemed to suggest that they were on cronicom's home world. if so, likely the 2 mentioned cronicoms brought them.

Huh? Nah. They were made on Izel's home planet by her race. Whoever from Izel's race stole the monoliths in the first place -- they never answered who that was this past season -- took them to Earth. So far, whoever it was took, took at least 4. And what I'm theorizing is the Kree from the rogue faction that made the Inhumans found one of the black ones. And like someone jailbreaking an iPhone, same deal here -- they decided to jailbreak the monolith and they figured out how to change the coordinates, ending up with this Maveth planet as the destination. And basically being the egotistical god complex folk they were, told the Inhumans the black monolith was their creation rather than admit some other superior race made it. But didn't matter in the long run since the Inhumans rebelled against them anyway.