Blood gets its red color primarily from hemoglobin, which is a protein found in red blood cells. Hemoglobin binds to oxygen and carries it throughout the body. When hemoglobin is oxygenated (bound with oxygen), it appears bright red, which is the color of arterial blood. Deoxygenated hemoglobin, which is found in veins, has a darker red color.
Myoglobin, on the other hand, is found in muscle tissue and serves to store and release oxygen as needed by the muscles. While both myoglobin and hemoglobin are similar in structure and function, they have different roles in the body.
In summary, blood is red because of the presence of hemoglobin.