When the Edain awoke in Hildórien and trekked all the way across Middle-earth into Beleriand, there were presumably tens of thousands who didn't fall under Melkor's deception and service, who were welcomed by the Sons of Finarfin in Nargothrond. Many of these Edain fought with the Host of Valinor in the War of Wrath by this point numbering in the hundreds of thousands but then they faced extreme casualties and by the time Númenor was raised there weren't as many as before the war. So how many Edain survived at the end of the First Age?
Less Than 14,999
The Peoples of Middle Earth talks about the migration of the Edain to Númenor.
The legends make no guess at the numbers, and the histories say little. The fleet of Elros is said to have contained many ships (according to some a hundred and fifty vessels, to others two or three hundred) and to have brought 'thousands' of the men, women, and children of the Edain: probably between five thousand or at the most ten thousand.
Whilst being vague and confirming that there is no concrete numbers an estimate of 5,000 to (an upper limit of) 10,000 Edain travelled to Númenor.
The Peoples of Middle Earth also suggests that this is the best part of the surviving Edain. It just took some time for them all to get there:
The legends of the foundation of Númenor often speak as if all the Edain that accepted the Gift set sail at one time and in one fleet. But this is only due to the brevity of the narrative. In more detailed histories it is related (as might be deduced from the events and the numbers concerned) that after the first expedition, led by Elros, many other ships, alone or in small fleets, came west bearing others of the Edain, either those who were at first reluctant to dare the Great Sea but could not endure to be parted from those who had gone, or some who were far scattered and could not be assembled to go with the first sailing.
But the whole process of migration appears in fact to have occupied at least fifty years, possibly longer, and finally ended only when Círdan (no doubt instructed by the Valar) would provide no more ships or guides.
But some must have stayed behind if Círdan was instructed to stop, implying some were still crossing piecemeal.
Therefore it can be fairly safely assumed that the majority of the Edain travelled in the first great fleet of Elros, with the remainder arriving in the following fifty years.
We can extrapolate from this that more than 5,000 Edain survived the First Age, as this was the lower limit of the main fleet to somewhere slightly over 10,000, the upper limit of the main fleet plus the stragglers.
If we take majority to mean greater than 50%, then we could suggest that no more than 14,999 Edain survived the First Age.