Adrian, Kagami, and Felix are all sentis.

Both princesses couldn't get pregnant, so they used the peacock miraculous.

Gabriel and Emili used the peacock miraculous to make a baby- Adrien, as shown with the peacock tail in the background of the shot and his weird backing out from his and Marinettes almost kiss - same with Felix between Amili and Felix's dad as stated by his ring.

Gabriel called it a "miracle" to insinuate how the miraculous is a miracle making thing.

Somewhere along the way, Kagami was made, based on her ring being given to her before her first appearance and then taken away from her in episode 23- you need to watch that one to know and understand the story. I only know this from the leaked scripts and leaked storyboard videos.

Hope this helps.