If you want your blog posts on another page than the home page, you need to assign a ‘static page’ to display it via the settings reading menu.
For your website, the ‘front page displays a static page’ option is probably selected. So you should assign a front page and a posts page. Your front page is probably correct as it is and your posts page should be your page named ‘blog’.
Be careful though before you make any changes. Be sure to write down the current settings if something goes wrong.