Math aside evolution cannot be understood by the average person. It is accepted on faith that science has correctly figured it out.
I'm an average person. I "get" evolution. I may not understand all of the minutia, and I couldn't tell you how, for example, genome sequencing works, but I understand, at a basic level, how it works, and how we know it worked like that. Because, honestly? Most of the evidence is pretty easy to understand.
Animals reproduce with slight modifications. Over time, these modifications can add up until the animal has changed phenomenally. This is
really basic, and the evidence for descent with modification can be seen every time you look at a family photo. It is therefore reasonable to assume that at some point, we shared a common ancestor. However, understandably, some people don't consider this particularly convincing, and demand more evidence.
"Viruses can insert themselves into replicating DNA and thus become part of our genetic code. We can find many insertion sites that are the same between us and chimpanzees, and if we compare insertion sites among all currently living animals, we can find degrees of similarity that match up to what the fossil record would tell us about the tree of life."
That's a bit difficult to wrap your head around, but by no means impossible. The problem is, people who reject evolution keep on saying "that's not good enough, that's not good enough" until the strongest evidence - stuff like ERVs or genetic similarities or the transposons in chromosome 2 - show up, they say "I don't get it, therefore it doesn't count". I'm sorry, but sometimes, things are a little complicated.
