You should better compare it with humans consuming stuff they created themselves. Or in a perhaps more sickening way, an author who only reads what they have written themself.

We know that there is more than one AI software but there is not as much variation as for humans.

And as someone else already wrote here, humans have something like a ratcheting mechanism. I would paraphrase it as "Humans have learnt to stand on shoulders of giants". AI does not have this.