Hi, welcome to web development; it’s a learning process.
Good to learn in your web browser how to “view source” for your web pages, this shows you exactly what is “rendered” for the web. This lets you check WHAT is actually seen by bots, Google, etc. See the help for your web browser on “how to view page source.”
You should be submitting your sitemap to Google, etc., via “search console” account (aka “webmaster tools”). This is how Google reads your sitemap to create elements for SERPS. If you don’t have a Search Console account for your website, good time to make one, and verify your site, then manage your sitemap(s) there.
h1 tag is for the body of your posts, not the <head> elements, where all your meta data lives.
Good luck!