1. "Deadpool was originally a ripoff of a DC Comics villain ... and it worked out OK"
So, Nicieza wasn't insinuating that Liefeld may not have known about a similar character at a competing company — it was patently impossible for Liefeld to not have been aware of Deathstroke. Here's Deathstroke over on the left.2. There's a lot going on in this headline.
Liefeld was proposing they create a very similar looking, similarly named, supernaturally agile assassin character, who even used the same weapons as a character who belonged to Marvel's biggest competitor.
What did the two young creators do in the face of this problem? Honestly, this is where the story reaches its wackiest point. They decided to lean into it.
Deathstroke's real name is Slade Wilson. So they named Deadpool "Wade Wilson."
3. Collection of Kris Anka's Harry Potter fan art.