Template with wordpress loop

I got this code from kategasis template, https://wordpress.pastebin.ca/1997516
this code is working properly if I use it for index template but why it cannot be displayed properly when i’m using as a page template ?

please help. I wanted to make a new page template consist of 1 newest post and the rest is 6 previous posts consist of titles only, please take a look at https://achmad.web.id