How to backup only the files used on my website

Over many years, I have kept everything from my previous websites/pages etc. that are not now needed because I am using WordPress now instead of HTML programming on 3 out of my 4 websites.

Being the pack-rat that I am, I always keep everything even when switching host providers, and switching to word Press. To be safe, I have downloaded everything I have onto my local computer, and it comes out to like 54 gigs, but I am pretty sure now that I am only using less than 5 Gigs.

I have 4 websites, 3 in Word Press, and 1 in HTML. I would like to find out exactly what directories, and files I need to keep for my 3 Word Press websites. Then when sure I will delete the others and directories and files. I am now switching host provider from Network Solutions to Host Gator, and would like to get and keep it clean as possible. Host gator offers a $50 a years cloud backup up to 5 gigs. but, I don’t want to destroy my sites by deleting the wrong files.

I noticed in dashboard, that when I hoover over items in the left column that it shows directories. I am assuming if I just keep those I would be safe?

Is there a program or way to tell word press to export all files and directories that are needed for the site to operate? Any suggestions are most welcome and appreciated!

Thanks