Blog page not showing posts

https://funtastickorea.com/blog/

My blog page does not show posts so I tried to copy the page.php codes, paste it in index.php (the file in WordPress folder and also in the Themes folder – not sure which one is correct).

I also tried deleting the blog page and re-creating a page named Blog, set the template to “Blog”, chenage the permalinks to https://funtastickorea.com/blog/ from https://funtastickorea.com/blog-2/.

I already have done this as well. “settings->reading”. Change “Front page display” to “A static page” and for the “Posts page:” choose your blog page.

Any ideas on what I can do to solve this problem? Much appreciated in advance!