I see everyone with these avatars which aren’t show with the 102 others. How do I obtain them or are the custom made and if so how can I do that

The extra avatars were granted to those who played the game during the first month of release. They are part off the compensation package offered by 343 for MCC not working. If you want to see if you are eligible to get them, check the FAQ post that I have stickied in the main MCC forums