[thaumasiotes]

Preexistence is still fully irrelevant. The generic use can come into being 50 years after the trademark does and it will still make the trademark invalid. Or it can die 50 years after the improper grant of a trademark and cause that trademark to become valid.

A descriptive term can't be trademarked, and using "super hero" to refer to stories about superheroes is descriptive. But there is no chronological consideration.

[s1artibartfast]

It is still relevant. The fact that it is preexisting is obvious evidence that it shouldn't have been granted or was immediately overturned on challenge.

The trademark office would not give me a trademark for "computers", "the internet", or "AI" if I walked in tomorrow

[thaumasiotes]

> The trademark office would not give me a trademark for "computers", "the internet", or "AI" if I walked in tomorrow

Again, so what? Would they give you a trademark on "The Bawdy House" for your chain of brothels? The problem with "computers", "internet", and "AI" is current usage, not former usage.

[s1artibartfast]

I don't understand what distinction you're trying to make between current and former.

Pre-existing and continuous usage is strong evidence that the current usage is not exclusive to your product.