Where did you get the part where Allah destroyed most of the jinn? Can you provide evidence?
Likewise fadlan could you please provide evidence where Allah says ibliss was the first jinn created?
He was the most pious out of the jinns but I don’t recall any Hadith or verses from the Quran that says he was the first jinn created, could you provide evidence?
There’s a whole chapter dedicated to the jinn in the Quran it’s called surah al jinn
“Say, [O Muhammad], "It has been revealed to me that a group of the jinn listened and said, 'Indeed, we have heard an amazing Qur'an.
It guides to the right course, and we have believed in it. And we will never associate with our Lord anyone.
And [it teaches] that exalted is the nobleness of our Lord; He has not taken a wife or a son
And that our foolish one has been saying about Allah an excessive transgression.
And there were men from mankind who sought refuge in men from the jinn, so they [only] increased them in burden.“
And they had thought, as you thought, that Allah would never send anyone [as a messenger].
And we have sought [to reach] the heaven but found it filled with powerful guards and burning flames.
And we used to sit therein in positions for hearing, but whoever listens now will find a burning flame lying in wait for him.
And we do not know [therefore] whether evil is intended for those on earth or whether their Lord intends for them a right course.
And among us are the righteous, and among us are [others] not so; we were [of] divided ways.“
https://quran.com/72
Your first question: I don't have a specific verse from the Qur'an, but I did hear it somewhere. I stumbled across this.
At-Tabari narrated in his Tafseer from Ibn ‘Abbas (may Allah be pleased with him) that he said:
The first ones to dwell on earth were the jinn, and they caused mischief therein, shedding blood and killing one another.
It was narrated from ar-Rabee‘ ibn Anas that he said:
Allah created the angels on Wednesday, and He created the jinn on Thursday and He created Adam on Friday. Then some of the jinn disbelieved, and the angels used to come down to earth to fight them, and there was bloodshed and corruption on earth.
Your second question: Allah clearly states the jins are iblees's offsprings, just like humans are Adams. Which I took to mean he is the first jin created, just like Adam is the first human created.
“Will you then take him (Iblees) and his offspring as protectors and helpers rather than Me while they are enemies to you?”
[al-Kahf 18:50]
Allah Knows best though.