Many think that color blind means you only see in black and white. That is completely FALSE. Being color blind means you cannot tell the difference between certain colors. You still see in color, it is just that in some cases 2 different colors look exactly alike to a person, or animal who is color blind. With humans it varies by person. To some red and black appear exactly alike, with others it could be blue and green.
Deer very much see in color, and camo certainly can help. It is most effective in preventing deer from seeing movement. Sitting perfectly still will make you all but invisible to most big game, but when it comes time move to shoot the camo will help.
Deer certainly do see in color, but to them the blaze orange that seems to jump out as something different to most human eyes simply blends in as a natural color to most big game. Most birds however have eyes most like humans, it really stands out to them.
Hunters have been trying to cover or disguise their scent for at least 10,000 years. Every group of people down through history have had their own methods. Today we buy it in a bottle or try to design clothes that will help eliminate scent. How effective it is may be questionable, but the principle is sound.