A handy list of #core-editor blocks for building Block Templates.
core/archives
core/audio
core/block
core/button
core/buttons
core/calendar
core/categories
core/classic
core/code
core/column
core/columns
core/cover
core/embed
core/file
core/gallery
core/group
core/heading
core/html
core/image
core/latest-comments
core/latest-posts
core/legacy-widget
core/list
core/media-text
core/missing
core/more
core/navigation-link
core/navigation
core/nextpage
core/paragraph
core/post-author
core/post-comments-count
core/post-comments-formcore/post-content
core/post-date
core/post-excerpt
core/post-featured-image
core/post-tags
core/post-title
core/preformatted
core/pullquote
core/quote
core/rss
core/search
core/separator
core/shortcode
core/site-title
core/social-link
core/social-links
core/spacer
core/subhead
core/table
core/tag-cloud
core/template-part
core/text-columns
core/verse
core/video