Basic migration question

Hi, I have what I hope is a really simple question getting in the way of me moving my site to WP.

I have a static html site of approx. 25 pages. I have selected a theme and all I really want to do is move the pages over to preserve the domain SERPS. I am happy to recreate the pages by copy and pasting content the manual way given the small size of the site, but I just want to ensure that I am able to redirect traffic from old to new.

I understand the concept of htaccess and 301 redirect but the thing stopping me is not understanding how the old homepage will be dealt with (index.html). For example, does this plugin just automatically deal with the homepage as part of the htaccess generation? Should WP be installed in a root subdirectory (even with this plugin) and is this longer subdirectory URL then visible to visitors when they browse the new WP site?

I’ve looked into many ways of doing this, including this plugin but I just don’t want to overcomplicate what might be a simple problem?

https://ww.wp.xz.cn/plugins/import-html-pages/