Time Machine stores backups as incremental changes, so each backup only contains the difference from the previous one, so your latest backup file only contains 8Kb of changes. This is the size reported by 'Get Info.' Your initial backup will contain a full disk image about 36Gb, and subsequent backups will contain just the changes, so your total disk space use is around 47Gb. The 13-off 36Gb folders you can see are sparse disk images, which have a symlink to the previous disk image and the changes due to the backup, but it looks just like a complete disk image to the user ( or time machine) because of file system magic.
TLDR; you have usable backup files if you keep everything.