Because it is implying all of those characters are also 100% original themselves. Some of them are, but most of them are also based on pre-existing ideas and concepts.

There are several historical quotes on the matter:

And before someone accuses me of "quote mining": no, none of these quotes are taken out of context. They are the full quotes by people with experience on the matter, from different fields.

In the end, originality is overrated. As a teacher of mine taught me, it does not matter if you created something new. What matters is if you created something useful. That is the true success of a creator, contrary to popular belief. And he should know: he is a computer engineering Ph. D. His job literally depends on creating value out of existing ideas – what do you know, just like videogames.

I don't know, most of those assumptions sound forced as fuck.