This ayat is not about 19 as a number it is about 19 angels and it should be viewed only in that way. Read the narrative of how these verses came to us and you will see just how wrong you are …
19 angels according to Ibn Kathir (RA) alludes to a number of angels found in the older scriptures. This is one of the great signs in that one of the great things Allah (SWT) created i.e. refering to Hell as an entity …
The thing is you can’t separate the verses from the Tafsir because in transmission the commentary was transmitted with the verses through the generations, until it reached Ibn Kathir (RA) who was one amongst others who told us what happened and why when these verses were being revealed.