Why do the Klingons keep getting rebooted?

But this has never been the case in any previous Trek show or novel in the past 50 years, only introduced for this show.

I thought worfs head was bigger earlier in the series but I alway assumed that was because he had longer hair in the later shows which hid his bulbus head size..

Star trek 2009 is a reboot that hasn't even shown us klingons. And alot of the "change" points you mention are not considered klingon reboots as the klingons haven't really changed much. Most people agree the only rebooted klingons stemmed from the 1979 addition of ridges on the head. The klingons from Discovery would be mistaken for a completly different species had the plot not mentioned they were klingons. The same can't be said of the other changes with the exception of 1979.

Also worth noting is the Bird of prey became a klingon ship despite its origin as a romulan ship. I always though the klingon battle crusiser just got more detailed but their two different ships. that are retconned to be klingon.

The Klingon social order I think was based on lion prides, since the Klingons are descended from an apex predator species. They're aggressive by nature but there are rules governing that aggression. If you challenge a superior's authority there's a single combat to the death and you either die or take their place. To their minds this is a good thing. It always makes sure the strongest are in charge and fools who are too ambitious for their ability are weeded out. What a civilization like this wouldn't be good at is advancing science and technology. From what they've said there was a race called the Hur'q who invaded their homeworld and ended up taking some of their cultural treasures when they left (including the Sword of Kahless). It was from them that the Klingons acquired space travel. Warp drive, energy weapons and shields, etc.

I'm pretty sure this is an alternate timeline. There may be a time travel arc at some point where the past is changed, and Klingon genetics with it, producing the "Prime" timeline we're familiar with. There are just too many inconsistencies for this to be the same world that leads to TOS.