The backups folder contains catalog backups. You can delete older ones to make room, but do keep some recents backups. It’s best to make backups to an external disk, but this is better than no backups at all.
I’m not sure what that downloads backups file is. Is that really a file, or perhaps a folder? if it’s a folder, then it probably is the destination of the ‘Make Second Copy’ option in the import dialog. This makes a temporary backup of the downloaded images. If you made a backup of these images in another way, then you can delete these backups.