Question

We humans are also matter so can we change into liquid and then to gas

Answer 1

The human body is a complex mixture of all phases of matter except plasma (the very hot stuff not the blood fluid) and including gas.
Bones are solid, blood is a mixture of liquid and mainly gelatinous red blood cells
Skin and flesh may seem fairly solid but are in fact a mass of cells of many types.
But as Sean Ridout says it does not make any sense to try and say, even on the molecular level, that a human is solid or gelatinous or whatever.
A lot of the macromolecules in a human body if extracted and purified can be crystallised but they behave totally differently when in the cells and fluids of the body.