Why would an AI start with a human utility function? Why would it care about that if it wasn't explicitly built in?
In the particular case of humans, our utility function(s) is(are) so complex that what we think of as our 'true values' can change (because our True values are some inscrutable tug-of-war between all the parts of the brain), and also we're hacked together by evolution, so just blindly trying to make a human smarter might change their values (or turn them mad, or cause seizures, or...).
But this doesn't have to be the case in general for intelligent agents. In principle, you can build an AI whose terminal values remain stable as it improves its intelligence. (If this is impossible, we're doomed.) So unless you explicitly built an AI to care about all humans, there's no reason to think it magically would.