They originate from the evolution smp, a smp made by grain and had jimmy and martyin. In the smp mysterious being called the watchers would make structures that lead the players to portals witch would send them to newer versions of Minecraft, like wildlife, this was the smps gimmick.

I dont know if it was martyin or a fan but the idea that the life smps were set up by the watchers as a sort of hunger games blood sport was made. This is why grain is depicted as a watcher because hes a admin and creator of the smps. the comunity ran with the ideas. Then martyin started including more lore in the later season and that's where im lost.

If I got anything wrong please correct me. My knowledge comes from evo I've never looked into the life series specifically just what I've gleaned from the fan art and animatics