Lost first backups - time machine
I think your first backups are most probably auto purged by Time Machine.

Time Machine automatically remove oldest backups when your backup disk is full. And Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month, and weekly backups until your backup drive is full.

Therefore there's no guarantee that your first backup(s) will be preserved.

You may try data recovery softwares on the Time Machine drive, but quite likely it won't help as Time Machine make new backup hourly and overwritten the old data.