I do consider Blade to be a super hero. More of an anti-hero though, because of the darkness, half vampire, vigilante side of his character. I do not believe skin color has any affect on determining weather or not he is a super hero. It's simple, he has super powers, and "takes care" of the bad guys, by injury or by killing them.
Blade is the first, he is a Marvel Superhero, he counts, he is the first. You can't change it up later and say well but this that etc. He is the first. They just don't want to go on record as saying a black character started the newer trend. He did, though. Blade got this party started. A black character is the first marvel super hero movie whether likes it or not.
The character of Blade was introduced from the beginning as a supporting character and the weight of his character was directly impacted by the slow development of the character by the author. The author notes that he had to mature as a write to fully realize a more realistic version of Blade's character.
Blade is a great super hero, regardless of his color. It's important that we judge our superheroes based on the merits, rather than just based on superficial things. Blade accomplishes a lot of good and he is powerful. Most people remember him for these things, rather than thinking that he'd be more or less depending on his color. He's a great and powerful regardless of his appearance.