How did humans procreate after the death of Habil?

Praise be to Allah.

Firstly:

There is nothing in the Qur’an or Sunnah to indicate that the progeny of Adam (peace be upon him) were limited to Qabil and Habil. Rather the scholars narrated that Adam (peace be upon him) had many children, from whom humanity are descended. This is what is indicated by the apparent meaning of the Qur’an, in the verse in which Allah, may He be exalted, says (interpretation of the meaning):

{O mankind, fear your Lord, who created you from one soul and created from it its mate and dispersed from both of them many men and women. Fear Allah, in Whose name you demand your mutual [rights], and be mindful of your ties of kinship. Indeed Allah is ever, over you, an Observer} [an-Nisa’ 4:1].

Ibn Jarir at-Tabari (may Allah have mercy on him) said:

It was said that Hawwa’ bore Adam one hundred and twenty sets of twins. The first of them were Qabil and his twin sister Qalima, and the last of them was ‘Abd al-Mughith and his twin sister Amat al-Mughith. Ibn Ishaq was quoted as saying that all the children that Hawwa’ bore Adam were forty children, male and female, from twenty twin pregnancies. And he said: The names of some of them have come down to us, and the names of others have not."(Tarikh al-Umam wa’l-Muluk  1/98).

Al-Hafiz Ibn Kathir (may Allah have mercy on him) said:

The historians stated that Adam (peace be upon him) did not die until he had seen four hundred thousand of his progeny – his children and grandchildren."(Al-Bidayah wa’n-Nihayah 1/96).

In addition to that, Muhammad ibn Ishaq – who is one of the scholars who had knowledge of lineages and history – stated that the lineages of all humanity go back to Shith ibn Adam, and that the lineages of the children of Adam other than Shith disappeared and became extinct. This is mostly taken from the People of the Book.

Ibn Jarir at-Tabari (may Allah have mercy on him) said:

All the descendants of Adam today are descended from Shith. That is because the progeny of all the sons of Adam except for Shith have disappeared and became extinct, and not one of them remains. So the lineages of all people today go back to Shith (peace be upon him). "(Tarikh al-Umam wa’l-Muluk (1/103). See also: at-Tabsirah by Ibn al-Jawzi (1/36, 24) and al-Bidayah wa’n-Bihayah 1/98).

Secondly:

With regard to the period between Adam and Nuh (peace be upon them both), this is stated in a hadith which was classed as sahih by some of the scholars:

It was narrated from Abu Umamah (may Allah be pleased with him) that a man said: O Messenger of Allah, was Adam a Prophet? He said: “Yes; he was spoken to.” The man said: How long was there between him and Nuh? The Prophet (blessings and peace of Allah be upon him) said: “Ten generations.”

Narrated by Ibn Hibban in his Sahih (14/69). It was also narrated by al-Hakim in al-Mustadrak (2/262); he said: It is sahih according to the conditions of Muslim, and adh-Dhahabi agreed with him. Ibn Kathir said in al-Bidayah wa’n-Nihayah (1/94): This is according to the conditions of Muslim, although he did not narrate it. Al-Albani classed is as sahih in as-Silsilah as-Sahihah (2668, 3289).

See also the answer to question no. 129959 .

And Allah knows best.