S. R. Faruqi:

It's possible that in this verse there might be an allusion to the story of two angels named Harut and Marut. About Harut and Marut, Rumi says (in the Masnavi, daftar 1, part 2) that they trusted in their own holiness, and that this arrogance deprived them of the grace of the Protector:

'They trusted in their own holiness--
As if a buffalo can trust in himself before a tiger!'

That is, holiness alone is an ill-equipped and stupid thing, like a buffalo, and lust (that is, the divine decree that manifested itself as lust) is lying in ambush like a tiger, alert and ready to kill. He goes on to say,

'What fear would a flame have of a heap of kindling?
Would a butcher flee from a herd of goats?'

The angels were struck down in their inappropriate confidence; Mir says, I am only a human-- neither do I have that honor that angels have, nor can I trust in anything. Even if I trusted, then so what? The beloved is like a flame and a man is like kindling, or the beloved is like a butcher and a man is like a goat.

The word ((i.smat is appropriate for angels no doubt, but with us in the idiom it's usually used for women's honor. Thus by using this word for the angels Mir has evoked, in addition to honor, the idea of forcible ravishment. This allusion is supported by the verses of Rumi's cited above.

In the second line, the colloquialism of kyaa ((aib is very fine; on the basis of it he has caused two phrases to do the work of three (If I committed a sin; then what of it; I was human). Another pleasure is that about his ((aib he feels no kind of shame at all. There's also a suggestion that his beloved is not less than the beloved of Harut and Marut, who shines in the sky in the form of the planet Venus. Then there's also the suggestion that Harut and Marut were two angels, their story is over. Even now, many angels are suitors of my beloved, and have become compelled to lose their honor before her beauty.

This theme he has again expressed in the second divan itself [{706,4}]:

ham bashar ((aajiz ;sabaat-e paa hamaaraa kis qadar
dekh kar us ko malak se bhii nah yaa;N ;Thahraa gayaa

[we are a weak human; to what extent would our foot remain steadfast?
having seen her, even angels were unable to endure to remain here]

But in that verse the expression of weakness seems artificial. In contrast to it, in the present verse there's a kind of stubborn defiance that in truth is on a human level.

[See also {733,2}.]

FWP:

SETS == IDIOMS; JO
MOTIFS
NAMES == ANGELS
TERMS

The idiomatic pleasures of kyaa ((aib are supplemented by the enjoyable colloquialness of the jo , which can have the same possibilities as kih (in 2a) and can also be a relative pronoun (in 2b). The result is to give the whole line a certain cavalier carelessness that works very well as a contrast to the first line.

SRF points to the story of Harut and Marut, but there are other, more general possibilities as well. The story in Qur'an 2:30-34 emphasizes the special chosenness of Adam as a divine 'viceroy', even though the angels point out in verse 30 how Adam will (in A. Yusuf Ali's translation) 'make mischief and shed blood'. God privately teaches him 'the names of all things', and then rebukes and humiliates the angels when Adam knows the names and they do not. The angels are then required to bow down before Adam (which they all do except Iblis).

Along these lines, if Adam has made some kind of a 'slip', it is first of all only to be expected (since the angels have noted that he was destined to misbehave), so that 'I was a human' can sound not necessarily ashamed, but perhaps at least slightly apologetic. But it'a also clear that Adam enjoys God's special favor, so that 'I was a human' can sound like a claim of privilege (Adam had a liberty and even license that the poor dishonored angels could only dream of).

And needless to say, Mir leaves it to us to decide for ourselves what this 'slip' might have been.