Is it true before we were created, Allah asked us do you want to be a angel or want to be a human?
The following verse has the answer for your question:
Indeed, we offered the Trust to the heavens and the earth and the mountains, and they declined to bear it and feared it; but man [undertook to] bear it. Indeed, he was unjust and ignorant. Quran (Al-`Ahzab - 72)
Tafseer (Explanation) Ibn-Kathir:
Al-`Awfi reported that Ibn Abbas said,
Al-Amanah means obedience.
This was offered to them before it was offered to Adam, and they could not bear it. Then Allah said to Adam:
I have offered the Amanah to the heavens and the earth and the mountains, and they could not bear it. Will you take it on!
He said, O Lord, what does it involve!
He said, If you do good, you will be rewarded, and if you do evil, you will be punished.
So Adam took the Amanah and bore it, and this is what is referred to in the Ayah: وَحَمَلَهَا الْإِنسَانُ إِنَّهُ كَانَ ظَلُومًا جَهُولًا (But man bore it. Verily, he was unjust and ignorant).
For more information, you can read the whole Explanation at: http://www.quran4u.com/tafsir%20ibn%20kathir/033%20Ahzab.htm