The Milky Way is not considered a giant black hole because it is not a black hole at all. The Milky Way is a large spiral galaxy that contains billions of stars, along with various other celestial objects such as planets, asteroids, and nebulae.
A black hole, on the other hand, is an extremely dense and compact object formed from the remnants of a massive star that has undergone gravitational collapse. Black holes have such strong gravitational forces that nothing, not even light, can escape their gravitational pull.
While the Milky Way does contain a supermassive black hole at its center called Sagittarius A* (pronounced "Sagittarius A-star"), the black hole itself is just a small fraction of the overall mass of the galaxy. The black hole at the center of the Milky Way has a mass equivalent to about 4 million times that of our Sun, whereas the total mass of the Milky Way is estimated to be around 100 to 400 billion times the mass of the Sun.
The Milky Way is referred to as a super-Galaxy because it is a large and complex galaxy, consisting of multiple arms spiraling out from its center. It is one of many galaxies in the universe and is part of a larger cosmic structure known as the Local Group, which includes several other galaxies such as Andromeda and the Triangulum Galaxy.
So, while the Milky Way does contain a black hole at its center, it is not itself a black hole. It is a vast collection of stars, gas, dust, and other celestial objects that form a spiral galaxy, and its supermassive black hole is just one component of its overall structure.