Why not? You’re the one making a strong claim. You should support it.
I have no idea what “a rare type of retrovirus” even means, but the question seems irrelevant to any point. Are you perhaps confusing retroviruses with endogenous retroviruses in the germ line?
A big problem you have, consistently, is that you ignore established results. Science doesn’t work that way. Science builds on past results to enable the interpretation of new results. One established result is that we know most of your genome is junk. (See Larry Moran’s book for illumination.) So no, I’m not ahead of myself. I just stand on the shoulders of giants.
This points out that your creationism is incapable of presenting well-formed hypotheses. We have no idea what a designer, particularly an omnipotent one, would or could do. We need to understand both the designer’s capabilities and his inclinations or purposes in order to make predictions. You have none of those, so your prediction is worthless. Why would a designer re-use sequences? If he had human limitations on effort, perhaps. But is the designer so limited? If he placed some aesthetic value on standardization, perhaps. But does he? Elsewhere, it’s been claimed that the designer glories in diversity, which would suggest that every species should have different sequences to accomplish the same purpose. And suppose the designer likes standardization, why do homologous ERVs differ so much in sequence both within and between species? So much for standardization. You really need to think about what you’re proposing and why. (Of course, evolution explains both the similarities, due to descent, and the differences, due to subsequent divergence.)