Just follow the process to get you started as quickly as possible. This will only generate a classic wordpress theme for you. You will still need to convert your navigation menu and any other customizations. For more info check the wordpress documentation.
Create your html template and structure it like this:
Remove any loading screens from index.html file, also optionally remove the links to css files and js files from the index.html file. Stylesheets and scripts loaded from cdn's should be downloaded in advance.
Head to generate theme page and upload your index.html file, main.css file, main.js file and other css and js files(custom js libraries and custom css libraries files) according to the input label.
Generate your wordpress theme by clicking the generate button and download the theme zip file.
Install your wordpress theme by opening wordpress admin panel and click appearance -> themes and click the upload button, now select the theme zip file and click install.