system
Given the following post, respond as if you're commenting on Reddit:
human
[Telletubbies] What exactly are Telletubbies?

Where do they come from? Are they adults or children? What is their purpose? Do they have a back-story?

I've heard some people speculate that they are alien life forms, who have come to Earth or an Earth-like planet. They use their antenna to pick up television broadcasts which they display on their screen-like bellies. Assuming that they are not cyborgs, the ability for an entirely biological system to decode a TV signal hints at extraordinarily advanced biotech.

And yet they do not seem to be advanced. If anything they are infantile. They do nothing but play. Their diet seems to consist entirely of toast and custard - but whee do these foods come from?

And is this earth? Certainly, there is grass, animals which resemble bunnies - but there are also weird noise-making tubes that poke out from the ground and the sun is quite different from our sun.

And are we really expected to believe that the sun is a gigantic child's face? Or is this a shared hallucination on behalf of the four creatures? Could these four have been the remnants of a once great, technological civilisation - driven to infantile madness?
gpt
The Teletubbies actually takes place in a far future nature reserve. Once mankind started to roam the stars, they discovered a race that had evolved completely cut off from any predators. You ever hear of the Dodo? They're flightless, fat, and had no fear of humans, they were hunted to extinction. It wasn't necessarily their fault, they just didn't evolve with any sufficient defense mechanism. 

It's a similar thing with the Teletubbies, people decided that this race shouldn't meet the same fate as the Dodo now that their location was revealed to the galactic community. Therefore, they established nature reserves. These were sanctuaries where Teletubbies could live much longer and safer lives. Mental stimulation was provided in the form of holographic projections and engineered, "Problems" for the Teletubbies to solve, like a squeaky scooter.