And your last paragraph about people believing in alien beings doesn't really relate to what I said. There are scientists who raise questions about evolution, and I don't believe that Americans who believe in presenting those questions in school are on par with the tiny group of Art Bell listeners who believe we didn't go to the moon.
Can you name a scientist, trained in biology (any specialty) who has published a peer reviewed paper questioning any of the basic tenets of evouion?
They only do that because the vast majority of anti-evolutionists cite Genesis as their prefered replacement to evolution. Science doesn't concern itself with religion, but the majority of anti-evolution people are religiously motivated. If you're the exception, great. But you've lumped yourself in with religious people, so, well, what can I say.
A question I have regarding similarities in DNA is: does that mean that all the animals came from the same original source? Or does it just mean that living creatures must have certain components to allow them to live on earth?
No. The reason is that retrovirus DNA inserts itself in any old random place in host DNA. The fact that we've inherited these fossilized remnants of virus DNA in exactly the same position as monkey and ape DNA means that it originated from a single infection in a single individual millions of years ago. No other explanation (other than religious) can explain it.
And your last paragraph about people believing in alien beings doesn't really relate to what I said.
What it relates to is that you mentioned something (to paraphrase) about the majority of Americans wanting to teach alternatives to evolution. My point is that Americans believe all kinds of stupid stuff like alien beings, yet we don't teach it in school just because people believe it's true.