Hulk's healing factor is all over the place. Sometimes he's more invulnerable and sometimes he's more of a healer. I'm not sure Hulk is a good healing factor benchmark.
The Hulk can be cut and impaled by things that should not affect one with true invulnerability, for example when he had spears embedded in him.
However, in another comic he was seen getting angry to the point that bullets made from Adamantium couldn’t pierce his skin. What’s interesting is that as he got angrier he got not just stronger but more ...invulnerable.
There was another time when some alien being was stating how thick his skin was (and that it would require a blade that could split an atom to cut it). Which is important, because to cut Superman (without first having to soak away enough of his solar reserves) has been done easily with a magic blade so sharp it could - yes - cut atoms.
Going back to the Hulk ...most people don’t get the character.
He is not some dumb strong brute, although that’s how he’s unfortunately written.
He is a reality warped that primarily manifests as strength, and it gets crazier/more powerful the angrier he gets.
This is why he can jump through a window that has chronogically-tempered glass that is meant to teleport him to another place if he breaks it ...and because he is so angry when he breaks through it does not work.
That is not ‘strength’ but something else.
Getting back on topic - Hulk does have a healing factor, and he has shown various levels of invulnerability ...but the thing about the character is he’s special.
Hey him angry enough, and I bet he could even get superspeed or flight ...