While our blood is iron based, some animals have copper based blood turning it blue. It is called hemocyanin. Human blood is red because of the presence of hemoglobin. Lobsters, spiders, molluscs, arthropods and other animals can and do in fact have blue blood.
Humans do not.
Neither rhesus negative nor rhesus positive people.
The claim that rhesus negative blood is copper based and that the term blue blood originates from copper based blood in rhesus negatives is a complete fabrication.
There are various speculations as to where the term “blue blood” origins and again: This is something man-made in terms of coining a phrase vs. science as it is.
A popular explanation for the term is that the royals tended to have paler skin than the average person who spent more time out in the sun. Because of the paleness, the veins were seen easily and the veins seen through the tissue looked blue.
This might be a reason why there was an assumption or myth that the royal families had blue blood. Copper-based rhesus negative blood is not it.
More here: Copper based blood and the color blue