Agree the default implementation of the Excel Importer is aimed quite technical .
You can create your own pages and logic to simplify the functionality for the “normal” user.
2 cents:
If the user wants full flexibility, then its hard to simplify > my first action would be; challenge the business on what they realllllyyyy want. These kind of requirements sounds to me like “We don’t have a proper idea, so if we can get the dev team make something flexible, then we don't have to think ourselves.”