Why does a helium balloon rise in air while ordinary balloon filled with air does not?

A helium balloon rises into the air because the density of the helium is lesser than the density of the air, therefore, the balloon rises, trying to reach above the air.

Helium is lighter than air, or to be more precise, less dense.

Helium gas weighs less than our atmospheric air so it floats. Same goes for hydrogen and a few other pure gases