You're working under the concept that anything that we can't reproduce in a lab or reliably witness in person is somehow unverifiable. This is not the case.
The scientific method allows for this by using hypotheses to predict what we would be able to test for, or witness, if a certain thing were true. For example, how would we know if the Hawaiian Islands were formed by plate tectonics vs. a hot spot in the earths magma that the plate was passing over? It is possible to make predictions on what we would find in these cases, and determine the correct answer, even though we cannot roll a time machine backward and see the Islands form.
Ichneumon has a great post on that subject here. I suggest you read it all thoroughly until you understand it.
You must accept or reject Genesis on faith alone. There is no way to verify the supernatural via science.
But science does give us methods to verify many things about the natural world, and Evolution has been thoroughly verified by many different methods. That's why it's presented as "fact". Because as well as we can determine, that's what it is.