ArcVieh

You can select images from media Library in the Widgets backend that will be shown on your Page. You can enter a size for the images.
The thumb-images will be linked to the full-sized-image. 
Requieres PHP 5!

Media Images Widget

Requieres PHP 5! You can select images from media Library in the Widgets backend that will be shown on your Page.

podpirate

Speed up your workflow by pasting files and image data directly into the WordPress media library.
You can copy files and image data from many desktop applications:
<ul>
<li>macOS Finder</li>
<li>Windows Filesystem</li>
<li>Screenshots</li>
<li>Adobe Photoshop</li>
<li>Gimp</li>
<li>LibreOffice</li>
<li>GoogleDocs</li>
<li>Adobe XD</li>
<li>SVG from Adobe XD, Illustrator, Figma and Affinity Designer (Note: An additional plugin for SVG Support is required. My favorite: <a href="https://wordpress.org/plugins/safe-svg/" rel="ugc">Safe SVG</a>)</li>
<li><a href="https://github.com/mcguffin/the-paste#applications-tested-so-far" rel="nofollow ugc">And some more…</a></li>
</ul>
… and paste it to Classic Editor or directly to the media library.
The most recent Desktop versions of Chrome, Edge, Firefox and Safari are supported.
Install <a href="https://wordpress.org/plugins/safe-svg/" rel="ugc">Safe SVG</a> to enable SVG support.
<a href="https://github.com/mcguffin/the-paste" rel="nofollow ugc">The paste at GitHub</a>
You like it? You can’t stop pasting? <a href="https://www.paypal.com/donate/?hosted_button_id=F8NKC6TCASUXE" rel="nofollow ugc">Paste some cash with PayPal</a>!
<h3>Known Issues</h3>
<ul>
<li>Firefox does not support pasting multiple files from the OS filesystem.</li>
<li>Safari lacks the support to convert images to the webP format.</li>
<li>Pasting in TinyMCE triggers a JavaScript error if <a href="https://wordpress.org/plugins/real-media-library-lite/" rel="ugc">Real Media Library</a> is active. Pasting in the media library is still working.</li>
<li>Edge is working suspiciously well, which is very unusal in the Microsoft world and must be considered a bug.</li>
</ul>

The Paste

This is a most excellent tool for giving your pasted images useful names, for your later reference and for better SEO. There's one extra step -- you don't simply paste into the editor, you have to tell it you're inserting an image and do your pasting in the media dialog.

It would be better if you could just paste in the editor and were asked for the filename automatically, but this is probably the best we can do via a plugin.

On my "essential" list

Paste files and image data from clipboard and instantly upload them to the WordPress media library.

Media Images Widget vs The Paste