Why Does My Takeout Have HTML Files In It?
They are readable summaries of your account data. For photos they can be ignored.
Takeout includes HTML pages so you can browse the export in a web browser without special software. There is usually an index at the top of the archive and smaller pages inside.
For a photo library they are not useful. The dates and places you need are in the .json files, not in the HTML, and the pictures themselves are plain image files.
You can leave them where they are and point a tool at the photo folders. Takeout JSON Metadata Fixer ignores anything that is not a photo, video or sidecar. It runs on your own computer and is free for your first 500 photos.