New user w/windows 10 ,webpages only load partially,esp. photos, even with blocking disabled and cache emptied

I'm running Windows 10 on a fairly new PC, which is kept updated and runs Avast anti-virus with a Zonealarm firewall. I migrated to Firefox after hearing bad things about Chrome's lack of security. Firefox has good reviews , in 2019, even if it is not the hip new choice that Opera and others are. After downloading it and getting set up ,and telling my security programs to consider it a friend, I noticed that Firefox loads a skeleton of a webpage, almost always . By skeleton , I mean very few pics, very few active links, just text. Blank spots where the thumbnails, links, and pics should be. Also on pages that do load and display photos, they disappear when the cursor is placed over them . Some webpages are still useable, others are not, due to this swiss cheese effect. Everything it decided to blank would fall into the "potential threat" category, so I did some reading, and experimented with clearing history , and unchecking the boxes blocking cookies and trackers, just to see if I could pinpoint the problem and allow the trusted sites or pages past it's filter. I had little success, and cannot really see myself living with the abbreviated versions of every webpage , which I don't think is what the huge majority ofFirefox users are relegated to . I just can't find that magic setting , and not due to lack of time or effort spent looking . I'd appreciate any help offered.