Depending on who you believe as much as 8% of human DNA has been altered (eg through a virus)Okay, I read the Wikipedia article on transposons. And...um...yes, how do they have anything to do with evolution, except as providing an engine for mutation, upon which evolution depends?
Evolution is "natural selection" based on Darwin's classic theory
A mutation is NOT always heritable (hence evolution is not fully valid)
If you want more detailed explanation as I said there are books on the matter (which obv go into more detail than say Wiki could possibly)
There must be variation among the traits of the individuals of a reproducing population, this variation must be heritable to some degree, and this heritable variation must have an effect on the differential ability of individuals to survive and reproduce in order for differential reproduction to occur. The individual variants that leave more offspring are said to be fitter or better adapted. Therefore, natural selection is usually described as differential reproduction resulting from differential fitness within a shared environment.
There also are more severe issues with us humans. Evolution in no way predicts or explains consciousness. Our brains are a severe issue with the evolutionary chain.