Disclaimer: this is purposefully obtuse.
Other effects in the game which explicitly state they kill you:
Shadows, succubi, massive damage, death saving throws, beholder death ray (notably not even their disintegration ray kills you), power word kill, vampires, mind flayers, night hags, drow inquisitors.
Clearly, if they intended for disintegration to kill you, they’d have said so. Since specific overrides general, and there is no general rule that disintegrated creatures are dead, I rest my case. QED.
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.