Question
Did people in Krishna’s time know that he was God?
Answer
The answer is both yes and no. Some people were aware about His divinity and some were not. Hence not even all the Gopis were aware that He is God and loved Him as an ordinary boy. There were various categories of Gopis out of which some were sages in previous lives, some were manifested form of Veda richas. They knew that Krishna was God, both other Gopis didn't.
Background 1
Out of all the gopis that loved Krishna some were married and some were unmarried. It is the unmarried girls who performed the Katyayani vrat because gods and goddesses when pleased grant boons. So because all the gopis in their heart loved Krishna they performed that vrat as it was customary and usual in those days for unmarried girls to perform vrat to get good husbands. This type of vrat is still present today in some form where girls perform kumara purnima puja to get good grooms.
Background 2
Draupadi knew the divinity of Krishna and hence called Him for help. Because it is only God who delivers the devotee from immediate danger. Gods and goddesses generally has to be pleased and many puja and rituals may be required for them. But Draupadi was in no situation for worshipping or keeping a vrat to please any god hence after being unable to defend herself with her own power she remembered Krishna for help as she knew his divinity.
Background 3
Arjuna didn't know that Krishna was God. He always considered Him as his friend who was mighty, intelligent and powerful. But he never ever thought that He could be God Himself. He was in doubt until Krishna showed Him His viswa rupa (universal form). Then only he realized Krishna as God and told as below:
sakheti matvā prasabhaṁ yad uktaṁ he kṛṣṇa he yādava he sakheti
ajānatā mahimānaṁ tavedaṁ mayā pramādāt praṇayena vāpi
yac cāvahāsārtham asat-kṛto ’si vihāra-śayyāsana-bhojaneṣu
eko ’tha vāpy acyuta tat-samakṣaṁ tat kṣāmaye tvām aham aprameyam [BG - 11.41,42]Meaning
Thinking of You as my friend, I have rashly addressed You “O Kṛṣṇa,” “O Yādava,” “O my friend,” not knowing Your glories. Please forgive whatever I may have done in madness or in love. I have dishonored You many times, jesting as we relaxed, lay on the same bed, or sat or ate together, sometimes alone and sometimes in front of many friends. O infallible one, please excuse me for all those offenses.
So not everyone was aware that Krishna was God. Some knew, some didn't know, and some came to know later. Due to lord's maya not everyone is able to know His divinity when He takes birth as a human [BG - 7.25,9.11]. (nāhaṁ prakāśaḥ sarvasya yoga-māyā-samāvṛtaḥ)
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