> Are we a result of similar microorganisms?
I'm no biologist, but from what I've read: Probably not. A really important fact about multicellular life is that each cell is genetically identical to any other cell in the organism. Otherwise, different cells will start competing with one another, until the relationship falls apart. In nature, symbiosis only works because each cell has an independent means of reproduction, and that always puts a limit to how close the cooperation can be (nothing close to forming multicellular life).