Thank you for reaching out to us. Those are the blog posts in Ethos demo you see, If you add a new post, it will automatically be displayed on your homepage. i checked your site and I see you've turned on the filterable index, please note that enabling the filterable index will bypass the standard output of your blog page, allowing you to specify categories to highlight, to show all of your posts, make sure to enter the correct IDs of the categories you want to showcase.
If you want to make a post featured, then edit your post in WordPress post editor, under Ethos Post Settings, enable Index Featured Post Layout (see screenshot)
Hope this helps!