I asked the roofer if he could put some nest material in the spot with the wood and he grabbed a bunch of twigs and built them a nice house. I wondered if they would nest in something that he had touched.
With the exception of vultures, birds have very underdeveloped olofactory lobes in their brains, which means they have little to no sense of smell. If a baby falls out of the nest, you can put it back without worry that the "smell" of a person will keep the parents from feeding the young.
Also--in answer to the original question--it depends. Typical birdhouses attract secondary cavity nesters. A primary cavity nester is like a woodpecker that creates the cavity, then nests in it. A bluebird is a secondary cavity nester that will nest in a naturally created cavity or a cavity created by a primary cavity nester the year or years before. If the birds that nest in your eaves will also nest in cavities, they may move to the birdhouse. If they are not a cavity nester but nest typically in trees, etc. it is quite possible you will have two sets of bird nests...
