Blog Template in Twenty-Eleven Theme?

You will have to create an new page in your themes folder and assign a template name to it. Please follow the link for reference and search “A Page of Posts”: https://codex.www.ads-software.com/Pages

OK, thank you. What if I want it to display all posts – i.e. – regardless of whether a category is specified or not?

Thanks.

Ed

You can list posts as WordPress default index page list:

<?php
// The Query
while ( have_posts() ) : the_post();
	echo '<li>';
	the_title();
	echo '</li>';
endwhile;
?>

For more reference: https://codex.www.ads-software.com/Function_Reference/query_posts

Do not edit the Twenty Eleven theme. It is the default WordPress theme and having access to an unedited version of the theme is vital when dealing with a range of site issues. First create a child theme for your changes.

no need for page templates – when you set the static front page, you also have the possiblity to set a posts page –

https://codex.www.ads-software.com/Creating_a_Static_Front_Page

Title the second page “Blog” (or you could call it “News”, “Articles”, etc.). This page will be a place-holder for showing the Posts on your site.
Do not use a custom Page template for this page! home.php or index.php will be used to generate this page.
DO NOT add content to the Blog Page. Leave it blank. Any content here will be ignored — only the Title is used.
Publish the Page.

afaik, the option only comes up if you have at least a second page for that.