If it makes a character into a non playable character option, what rule is suddenly making that character playable? Nothing explicitly states that you can play as a character that is not a playable character option. You have a set list of RAW character options.
You seem to not be understanding so let me break it down.
Playable - you can play as this
You have a list of playable character options in the character creation section of the phb, and additional ones provided by sourcebooks.
If it isn’t a playable character option, it isn’t playable. RAW. It isn’t an option. It isn’t playable.
RAW. Let me get that through your head.
“Rules as written”
Not RAI.
Not “rules as intended”
RAW.
Written.