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 جَعَلْنَـهُ 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,

إِلَى قَدَرٍ مَّعْلُومٍ - فَقَدَرْنَا فَنِعْمَ الْقَـدِرُونَ

(For a known period. So We did measure; and We are the Best to measure) 77:22-23 meaning, for a known period of time, until it is established and moves from one stage to the next. Allah says here,

ثُمَّ خَلَقْنَا النُّطْفَةَ عَلَقَةً

(Then We made the Nutfah into a clot,) meaning, `then We made the Nutfah, which is the water gushing forth that comes from the loins of man, i.e., his back, and the ribs of woman, i.e., the bones of her chest, between the clavicle and the breast. Then it becomes a red clot, like an elongated clot.' `Ikrimah said, "This is blood."

فَخَلَقْنَا الْعَلَقَةَ مُضْغَةً

(then We made the clot into a little lump of flesh,) which is like a piece of flesh with no shape or features.

فَخَلَقْنَا الْمُضْغَةَ عِظَـماً

(then We made out of that little lump of flesh bones,) meaning, `We gave it shape, with a head, two arms and two legs, with its bones, nerves and veins.'

فَكَسَوْنَا الْعِظَـمَ لَحْماً

(then We clothed the bones with flesh,) meaning, `We gave it something to cover it and strengthen it.'

ثُمَّ أَنشَأْنَـهُ خَلْقاً ءَاخَرَ

(and then We brought it forth as another creation.) means, `then We breathed the soul into it, and it moved and became a new creature, one that could hear, see, understand and move.

فَتَبَارَكَ اللَّهُ أَحْسَنُ الْخَـلِقِينَ

(So Blessed is Allah, the Best of creators.)

ثُمَّ أَنشَأْنَـهُ خَلْقاً ءَاخَرَ

(and then We brought it forth as another creation. ) Al-`Awfi reported that Ibn `Abbas said, "We change it from one stage to another until it emerges as an infant, then it grows up through the stages of being a child, adolescent, youth, mature man, old man and senile man." Imam Ahmad recorded in his Musnad that `Abdullah -- Ibn Mas`ud -- said, "The Messenger of Allah ﷺ, the Truthful One, told us:

«إِنَّ أَحَدَكُمْ لَيُجْمَعُ خَلْقُهُ فِي بَطْنِ أُمِّهِ أَرْبَعِينَ يَوْمًا نُطْفَةً، ثُمَّ يَكُونُ عَلَقَةً مِثْلَ ذلِكَ، ثُمَّ يَكُونُ مُضْغَةً مِثْلَ ذلِكَ، ثُمَّ يُرْسَلُ إِلَيْهِ الْمَلَكُ فَيَنْفُخُ فِيهِ الرُّوحَ وَيُؤْمَرُ بِأَرْبَعِ كَلِمَاتٍ: رِزْقِهِ، وَأَجَلِهِ، وَعَمَلِهِ، وَهَلْ هُوَ شَقِيٌّ أَوْ سَعِيدٌ، فَوَ الَّذِي لَا إِلهَ غَيْرُهُ إِنَّ أَحَدَكُمْ لَيَعْمَلُ بِعَمَلِ أَهْلِ الْجَنَّةِ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَهَا إِلَّا ذِرَاعٌ، فَيَسْبِقُ عَلَيْهِ الْكِتَابُ فَيُخْتَمُ لَهُ بِعَمَلِ أَهْلِ النَّارِ فَيَدْخُلُهَا، وَإِنَّ الرَّجُلَ لَيَعْمَلُ بِعَمَلِ أَهْلِ النَّارِ حَتَّى مَا يَكُونُ بَيْنَهُ وَبَيْنَهَا إِلَّا ذِرَاعٌ، فَيَسْبِقُ عَلَيْهِ الْكِتَابُ فَيُخْتَمُ لَهُ بِعَمَلِ أَهْلِ الْجَنَّةِ فَيَدْخُلُهَا»

(The creation of anyone of you is gathered for forty days in his mother's stomach as a Nutfah, then he becomes a clot for a similar period of time, then he becomes a little lump of flesh for a similar length of time. Then the angel is sent to him and he breathes the soul into it, and four things are decreed: his provision, his life-span, his deeds, and whether he will be wretched or blessed. By the One besides Whom there is no other god, one of you may do the deeds of the people of Paradise until there is no more than a forearm's length between him and it, then the decree will overtake him and he will do the deeds of the people of Hell and thus enter Hell. And a man may do the deeds of the people of Hell until there is no more than a forearm's length between him and it, then the decree will overtake him and he will do finally the deeds of the people of Paradise and thus enter Paradise.) This was recorded by Al-Bukhari and Muslim.

فَتَبَارَكَ اللَّهُ أَحْسَنُ الْخَـلِقِينَ

(So Blessed is Allah, the Best of creators.) means, when Allah mentions His ability and subtlety in creating this Nutfah and taking it from stage to stage until it takes the shape of a perfectly formed human being, He says,

فَتَبَارَكَ اللَّهُ أَحْسَنُ الْخَـلِقِينَ

(So Blessed is Allah, the Best of creators.)

ثُمَّ إِنَّكُمْ بَعْدَ ذلِكَ لَمَيِّتُونَ

(After that, surely you will die.) means, after first being created from nothing, you will eventually die.

ثُمَّ إِنَّكُمْ يَوْمَ الْقِيَـمَةِ تُبْعَثُونَ

(Then (again), surely you will be resurrected on the Day of Resurrection.) means, you will be created anew.

ثُمَّ اللَّهُ يُنشِىءُ النَّشْأَةَ الاٌّخِرَةَ

(and then Allah will bring forth the creation of the Hereafter) 29:20 means, the Day of Return, when the souls will be restored to their bodies and all of creation will be brought to account. Everyone will be rewarded or punished according to his deeds -- if they are good then he will be rewarded, and if they are bad then he will be punished.