Greatest debut album

Inner Mounting Flame imho does not qualify as a debut. John McLoughlin did two LPs on Douglas - after he left Miles’s Bitches Brew band, before he formed the Mahavishnu Orchestra. 

My best debut LPS would be, in no particular order, excepting The Doors which for me is a clear Numero Uno:

The Doors - The Doors
Laura Nyro - More Than a New Discovery
Jeff Buckley - Grace
Little Feat - Little Feat
Mark Almond Band - Mark Almond Band
Joni Mitchell - Songs of the Seagulls
It’s a Beautiful Day - It’s a Beautiful Day
Crosby Stills Nash - Crosby Stills Nash
David Crosby - If Only I Could Remember My Name
The Byrds - The Byrds
The Flying Burrito Brothers - The Guilded Palace of Sin
Gram Parsons - GP (unless you think of The FBBs as a Gram Parsons backup band, which imo they are not: Chris Hillman was a huge contributor)
Public Image Limited - Public Image Limited
The Gang of Four - Entertainment!
X Ray Spex - X Ray Spex (a one hit wonder, I am afraid)
Scraping Fetus Off the Wheel - Nail
Chicago - Chicago
Hot Tuna - Hot Tuna

Wcfeil you are correct.

At 64 years of age, the brain cells are dying by the trillions as I write this. By the time I hit post, I’ll be ready for assisted living.

Add to the fact fact that I have 6,000 LPs, excuse me if I don’t remember all the titles like I once used to.