Well done, Max!
you've grasped that When air has a free, unrestricted path convection heat rises.
Now we've just got to get your mind to comprehend a few other basic fundamentals.
...Oh, and that there was no free, unrestricted path of airflow within the building... there was a crippled building in the way.
-but you're getting there... perhaps.
Convection through a solid? -Um... No.
Convection as the dominant heat dissemination? -Ummmmmm.... No.
RADIATED heat doesn't just travel upwards: otherwise the bottom of a patio grill would be cold.
CONDUCTED heat doesn't just rise, otherwise the metal shaft of my Soldering iron would serve as a useful handle, providing I kept the element and tip upright.
No. CONVECTED heat is the heat which is carried by warmed gases. Warming gases expand, and thus rise, carrying their latent absorbed heat with them. If that were the only source of heat transfer, the floors below would be stone cold... but it ISN'T.
Try and grasp that instead of over-simplifying with statements like: "heat travels upwards.. otherwise you'd put the pot UNDERNEATH the fire.. "
Radiated heat travels downwards just as well as upwards. -and sideways too! Above a fire, a pot will boil quicker, becasue of the addition of convected gases contacting the pot... but conduction and radiation are ignorant of direction... and if you obstruct or redirect the rising gases, you diminish the convective effects.
Deny that if you like, and proclaim yourself a bigger fool!
Keith