You want the front page of your website to display the latest posts, so you have two choices;
Option 1/ In ‘Settings’ > ‘Reading’, set the ‘Your homepage displays’ option to ‘Your latest posts’
With this setting, your front page will only display your latest posts, and nothing else, and the transparent header page template will not work.
Option 2/ Create a page, name the page whatever you like. On that page add the “Latest Posts” block, select “Grid View” and choose the options (excerpt, display date, featured image, sorting, number of items, columns etc) for that block. Add any other content blocks you want to the page. Set the ‘Template’ for that page to transparent header.
Then in ‘Settings’ > ‘Reading’, set the ‘Your homepage displays’ option to ‘A static page’, and for the ‘Homepage’ option select the page you have just created. You can leave the ‘Posts page’ option empty as you won’t be needing it.
Now, with this setting, your front page will display your latest posts, and also any other content you have added to the page, and the transparent header page template will work.