Current Superman and Lois are not part of America's greatest generation because of vague, unfulfilled slogans like "one timeline where everything matters".
You act like current Superman's life on Earth involves a single conglomerated timeline that would necessarily involve his career emerging in 1940s America and dealing with World War II.
That notion is farcical. You'd have to ignore the very follow-up to Death Metal itself which is Infinite Frontier #0. In it, the Quintessence reveal to ascended Wonder Woman that the DC multiverse was restored. Not "one timeline" but "countless universes" worth of timelines:
Once you're done ignoring the specific follow-up to Death Metal, you'd then have to argue against 40 years of published DC comics since Crisis on Infinite Earths where it is established that current Superman did not emerge in the 1940s.
And don't forget to resolve you arguing with yourself since you ironically dispelled that notion when you posted Superman fighting during World War II only because he was sent back to that time via time-travel!
What ought to be pointed out is that I'm not the one trying to ignore the consequences of Death Metal, much less 80 years of DC comics publication. I embrace it, together with all its famous retcons. You're the one trying to ignore it in favor of a throwaway slogans that are repudiated by the actual comics themselves.
Oh, deja vu?