Assalaamu alaykum.
“We will say to Hell on the Day of Ressurection, ‘Have you been completely filled up?’ And it will say, ‘Is there anything more?’” And he stated on the authority of Anas ibn Malik that the Prophet, sallallaahu 'alayhi wa sallam, said, “(The sinners) will be thrown therein, and it will continue to say, ‘Is there anything more?’ until Allaah, the Exalted and Glorious, will keep His foot therein, and some of its parts will draw close to the others, and it will say, ‘Enough, enough, by Thy Honour and by Thy Dignity,’ and there will be enough space in Paradise until Allaah will create a new creation, and He will make that spare place in Paradise accommodate them.” (Muslim 2848; Bukhari vol. 6/273)
Can you please explain the nature of the new creation in Paradise according to the pious predecessors?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

The authentic ahaadeeth proved that Allah will create a creation and make them dwell in Paradise. The ahaadeeth did not clarify the nature of that creation, but what comes to the mind is that they are like humans.

You should know that the matters of the Hereafter are part of the Unseen which can only be known by revelation. Hence, we cannot delve into the issue of how this creation is by our opinion, intuition, or assumption. We must believe in the revelation that was revealed about this according to what is mentioned in it, and if the revelation did not clarify something, then there is no way for us to know it.

Shaykh Is-haaq Ibn Abd Ar-Rahmaan Aal Ash--Shaykh was asked about what was reported, that the Prophet saw Moosa (Moses)  praying in his grave, and he saw him performing Tawaaf (circumambulation) around the Ka'bah, and he saw him in the heaven, and he also saw other Prophets; and he replied, “We have to believe in these ahaadeeth as they were reported, in their literal meaning, as there is no room for our mind to know them. Indeed, whoever opens this door for himself in this field, he will undoubtedly be doomed.”

Therefore, we advise you to stop researching and delving into the matters of the Unseen that have not been clarified in Islamic texts. The scholars stated that asking too many questions about matters that a person does not need is a reason for being misguided and deviated from the Truth.

Ibn Battah said in Al-Ibaanah:

“You should know, my brothers, that I have thought about the reasons that drove some people out of Ahlus-Sunnah wal-Jamaa’ah and forced them into innovation and hideousness and opened the door of afflictions of the hearts  for them and blocked the light of truth from their insight. I found out that this is due to two reasons:

1- Searching and delving into so many questions about useless matters which do not harm a rational person if he is ignorant of them and which do not benefit a believer if he understands them;

2- Sitting with those who may be a source of Fitnah (temptation, tribulation) and whose company corrupts the hearts.”

Then he mentioned some ahaadeeth that deter the Muslims from asking too many questions, among which is the following hadeeth: “Verily, the people before you were destroyed because of their excessive questioning and disagreeing with their Prophets.”

Allah knows best.