No? Deadpool says he's essentially a mutant.
Deadpool saying
"I'm mostly-sorta-kinda-basically-essentially a mutant" is a very bad counter-point to him not being a mutant. You're either intentionally or unintentionally misreading the tone. It's the same as going:
"My sister once knew a girl that dated Bruce Wayne, so him and I are kinda best friends."
He's an X-Men fanboy and would love to be considered a mutant to be more alike Wolverine; he's not/was not though. If I'm not mistaken, he's trying to get on Krakoa in those panels and they won't let him in because he's NOT a mutant.
It's on this very same island he gets reborn as a mutant.
Deadpool is not/was not a mutant for the vast majority of his time in media. I don't understand the confusion.