Turns out this worked (the thread in stack exchange)! And I didn't have to upgrade my version of PHP. Now, I just need to learn how to use it! Thank you for all of your help!
I can't post the code that actually worked (the forum didn't like the HTML), but it was the last one in the thread.
Yes, it's the stack exchange link that you shared with me. The last solution suggested worked. However, how my menu items aren't working. I know from videos that there is supposed to be a flyout menu, but nothing happens when I click the links.
I replaced this line of code, and now the icons are visible and the main link works, but no flyout menu:
<item name="view_preprocessed" xsi:type="object">Magento\Framework\App\View\Asset\MaterializationStrategy\Symlink</item>
<item name="view_preprocessed" xsi:type="object">Magento\Framework\App\View\Asset\MaterializationStrategy\Copy</item>
I found a threat that fixed this: