Endogenous retroviruses (ERVs) are segments of DNA which, due in part to some similarities and their seemingly haphazard distribution, are thought to have resulted from past viral infections.... and so on.
Even if this idea were correct, it does little to support evolution in the microbes-to-man sense.
This is part of a larger Creationist scheme-- put words like 'purportedly' and 'supposedly' in front of basic scientific facts. Create confusion in followers by making facts relative. "We look at a sequence and see GOD! Scientists look at a sequence and see MUTATION! Same data, different interpretations... You arent a MUTATION, are you?"
The LTRs of ERVs are distinctive enough that we can sometimes determine what kind of retrovirus the ERV used to be (alpha, beta, etc). We can even find families of related ERVs and reconstruct an infectious retrovirus from their leftover bits. There is no other way to 'interpret' this data, other than stating that ERVs are ERVs.