Christopher Reeve and the guy in Superman Returns were in their 20s when they played Superman. Dwayne Johnson is in his goddamn 40s. Can you guys seriously not think of any young black actors?
The OP does say you can pick someone who’s too old now but would have been good in their prime.
One who’s still young enough now and tall/strong/handsome enough would be [Aldis Hodge - IMDb] Aldis Hodge. I’ve only seen him play a fairly comedic character in Leverage, but I reckon he could pull off Superman’s quietness too.
Maybe this isn’t playing the game right, but I’d say why not cast a relative unknown? That is, someone not so famous that tim314 has ever heard of them. I had never heard of Henry Cavill before he was in Man of Steel, nor of Christian Bale before he was in Batman Begins.
Fair enough, I guess I’m just irrationally annoyed that we’re asked to name a black actor and the only names people can think of are people who would need to be resuscitated to play the role.
Dwayne Johnson doesn’t look 40 and he could probably do a better job of throwing a villain across a street without benefit of special effects than any of the other actors mentioned.
Besides which, a younger actor isn’t going to have very much work under his belt yet, and so we wouldn’t expect to have heard of him. Which is of course why parts do usually go to relative unknowns, and why none of us here are casting directors.
However, Kirk Alyn (who played him in the 40s serials) and George Reeves (who played him in the 50s TV series) were both in their late 30s (38 and 37, respectively, in their first appearances as the character), and Henry Cavill (who played him in Man of Steel) was just turning 30. Tom Welling (who played Clark in Smallville) was in his early 20s when he started…but he was playing a high school student at the time.
When Alyn, Reeves, and Reeve played Superman, the comics portrayed him as a man in his mid-late 20s - making Reeve the only one of the three to be playing even close to his actual age - and Superman Returns was a direct sequel to Superman II, set 5 years later, so the fact that Brandon Routh was the same age as Reeve was in Superman makes him about 8 years too young.
Apparently, Man of Steel portrays Superman as 33 years old (according to Cavill…I totally didn’t get that from the movie, personally), putting Cavill at pretty close to the right age, but being something of a strange choice, since MoS shows him just starting out. (The current comics, which MoS is aesthetically closest to, explicitly depict Superman as 28, six years after he got his start.)
Also, several actors in their 20s and early 30s have been suggested in this thread (most of whom are too babyfaced, IMO, unless this prospective Black Superman Movie is Smallville-style and starts with him in high school).
Jesse Williams of a little show called Grey’s Anatomy. Chadwick Boseman was just in a petty big film. How about Mehcad Brooks? Michael B. Jordan (who I believe somebody named)? Jay Ellis? We have more options that Samuel L. Jackson and Carl Weathers. I’m still rooting for Charles Michael Davis in this imaginary film.
In reality it probably would be a relative unknown (or complete unknown). The thread was asking who “we” would cast, not who we think would actually get cast, and I’m not sure how we’re supposed to suggest people we’ve never heard of.
OTOH, Aldis Hodge probably is relatively unknown, so he’s actually in with a chance, if it happened in the next couple of years (it won’t). I’ve changed my mind about Idris Elba because Superman really should be played by an American. I know the current actor is British, but I don’t think it’s quite right - certain characters are tied to certain countries.
Maybe he should be Ma Kent instead.
Back in the day it would have been Billy Dee Williams. ALways had a thing for him in my dim and distant youth.
Today, hands-down, Shemar Moore for the win. Oh my. Oh my my my… 
Rick Fox
Ah, definitely a good choice.
I don’t like Williams for the role, though. In his prime he was TOO skinny. Shave his head and he’d have made a pretty good Lex back then, though. Now, too, if you go with the 80s/90s take, where he’s significantly older than Clark.
Old Spice Guy. I don’t know if he can act, but he has the body for it.
StG
Of course he can act. He’s an excellent actor. He could play Macbeth, Hamlet, and Oberon. In the same play. On a horse.
I’ve been thinking about why I can’t think of anyone appropriate (even Poiter, who also would have looked damn fine on a horse in his day), and I have to say, good black actors these days just have too much depth. Maybe it’s the movies I watch.
Damn it! When I saw the thread title that was the first name that popped into my head!
Why not Red Fox? 
slap! Ow!
How about Michael Warren in his prime?
Jesse Williams! He’d be perfect!
My distant second choice would be Taye Diggs. Shemar Moore and Tyson Beckwith tie for third.
Eddie Murphy as Superman. And Lois Lane. And Jimmy Olsen, and Lex Luthor and Perry White… Hilarity ensues.
This … and, what is with this agist crap lately? Young people can only focus their eyes and attention span on their peers, and even a lot of older folks are buying into the “barely out of adolescence” requirement for beauty, and “must look twenty-something” popularity. The obvious exceptions, Johnny Depp and James Spader, are already at the pasture gate, so to speak.
Back in the “don’t trust anyone over 30” seventies, there were all kinds of attractive middle-aged actors who appealed to younger viewers … Rockford Files, Magnum, P.I. I suppose Miami CSI and Burn Notice, as they sail into the West, were the last of the “older folks can be hip” era.
Dwayne Johnson would have made a much better “Conan” and could absolutely be Superman. He looks like an alien with superior molecular structure.
Now, who will play Lois?
Robert Downey Jr