Not to mention, flu deaths are attenuated by flu shots, and pre-existing immunity. It's totally plausible that there are many more COVID cases than flu cases in that age group -- and of course those flu deaths will happen year after year while COVID is a very stable virus, and if you get it once, you probably won't get it again.
Certainly not enough data to conclude it's way out of line with the flu for this age group, in this season let alone if you factor in a few seasons end on end.
Lastly, with H1N1, the numbers are quite different, too.
The infection fatality rate for seasonal flu [edit: in the slightly older 18-49 group] is around 0.2% considering symptomatic cases, and probably there are as many asymptomatic cases which give 0.1%.
So yes, it's not impossible for the infection fatality rate to be similar. With some strong assumptions including that it's five times as contagious. So yes, it's not impossible for the acumulated lethality over five years to be similar. And if you extend the period the common flu will be much more dangerous, specially as this young people became older.
There are 400 covid-19 deaths reported so far in the 18-44 age group in NYC. There are 3.5 mn people in that age group in NYC. That's over 11 per 100'000.
The mortality per 100'000 for the 18-49 group in the US estimated by the CDC was in the last nine flu seasons: 1.8, 2, 1, 1.2, 0.7, 2.5, 1.5, 0.5, 3.9.
It's a stretch to say they are approximately the same and definitely 11 is not better than 0.5-3.9.