Allah tells:

وَلَقَدْ خَلَقْنَا الْإِنسَانَ مِن سُلَالَةٍ مِّن طِينٍ ﴿١٢﴾

And indeed We created man out of an extract of Tin.

Allah tells us how He initially created man from an extract of Tin. This was Adam, peace be upon him, whom Allah created from sounding clay of altered black smooth mud.

Ibn Jarir said,

"Adam was called Tin because he was created from it.''

Qatadah said,

"Adam was created from Tin.''

This is the more apparent meaning and is closer to the context, for Adam, upon him be peace, was created from a sticky Tin, which is a sounding clay of altered black smooth mud, and that is created from dust, as Allah says:

وَمِنْ ءَايَـتِهِ أَنْ خَلَقَكُمْ مِّن تُرَابٍ ثُمَّ إِذَآ أَنتُمْ بَشَرٌ تَنتَشِرُونَ

And among His signs is this that He created you (Adam) from dust, and then -- behold you are human beings scattered! (30:20)

Imam Ahmad recorded from Abu Musa that the Prophet said:

إِنَّ اللهَ خَلَقَ آدَمَ مِنْ قَبْضَةٍ قَبَضَهَا مِنْ جَمِيعِ الْأَرْضِ، فَجَاءَ بَنُو آدَمَ عَلَى قَدْرِ الْأَرْضِ، جَاءَ مِنْهُمُ الْأَحْمَرُ وَالْأَبْيَضُ وَالْأَسْوَدُ وَبَيْنَ ذلِكَ، وَالْخَبِيثُ وَالطَّيِّبُ وَبَيْنَ ذلِك

Allah created Adam from a handful which He picked up from throughout the earth, so the sons of Adam came forth accordingly, red and white and black and in between, evil and good and in between.

Abu Dawud and At-Tirmidhi recorded something similar.

At-Tirmidhi said, "It is Sahih Hasan.''

ثُمَّ جَعَلْنَاهُ نُطْفَةً ...

Thereafter We made him a Nutfah.

Here the pronoun refers back to humankind, as in another Ayah:

الَّذِى أَحْسَنَ كُلَّ شَىْءٍ خَلَقَهُ وَبَدَأَ خَلْقَ الإِنْسَـنِ مِن طِينٍ

ثُمَّ جَعَلَ نَسْلَهُ مِن سُلاَلَةٍ مِّن مَّآءٍ مَّهِينٍ

and He began the creation of man from clay. Then He made his offspring from semen of despised water. (32:7-8)

meaning, weak, as He says:

أَلَمْ نَخْلُقكُّم مِّن مَّآءٍ مَّهِينٍ

فَجَعَلْنَـهُ فِى قَرَارٍ مَّكِينٍ

Did We not create you from a despised water, Then We placed it in a place of safety. (77:20-21)

meaning the womb, which is prepared and readily equipped for that,