[Tuor in Gondolin]

Well, of course in a way the Numenorians did exist in the First Age (as the Edain of the three houses fighting Morgoth)- Tuor, Turin, Beren One-Hand, etc.). While individually not quite up to the greatest human warrior of all (Turin) the Numenorean forces were said to be the greatest army since the Valar finally intervened at the end of the First Age- but then Sauron was a weak imitation of Morgoth.

But of course, fighting with the elves under the ban, and without Earendil, Eagles, and the angelic Valar and Maiar they would at most have bought time, not overthrown Morgoth---although if they had siege and fortress storming techniques which the elves clearly did not (banging on metal gates to be let in isn't frightfully effective) they could have made things interesting. But it would need to be the Numenorians of say Tar-Aldarion, not Ar-Pharazon.