Question

are gases also considered as fluids

Answer 1

The definition from the 1st source below is: a fluid is any substance that flows or deforms under an applied shear stress. Fluids comprise a subset of the states of matter and include liquids, gases, and plasma.

The problem seems to be your concept of a fluid. Since you can move freely through a gas, i.e., air, that is a property of fluids. Some think of liquids only as being fluids, but the full extent of the definition includes gases as well.

Look at the video link and it will show you that air (cold CO2) actually flows. That is one of the ways you can see the fluid property of a gas.