Apart from the default <div> which in HTML semantics is Division and has no explicit meaning – the others are known as Section Elements that are also ARIA Landmarks – see here:
https://www.w3.org/TR/wai-aria-practices/examples/landmarks/HTML5.html
In your instance the <header> would be the correct element tag – as you’re replacing the Site Header. Browsers and importantly Screen readers and other assistive technologies use these landmarks to assist navigation. Its also good HTML semantics as someone reading the code can see here is the header, here is the footer.
In regards to the <aside> you will see this in places such as a Widget.