With all due respect, but what you're saying is absolute nonsense.
When it comes to popularity Superman is still No.1 to the wider general public, don't believe me? check out those links below:
This has to be good news for Warner Bros., which plans to release the Superman reboot Man of Steel [...]
comicbook.com
The one above is a yahoo front page poll in 2013 with over 138 thousand votes and our boy Kal b**ch slapped both Spidey and comicbooks's most overrated superhero who doesn't have superpowers aka Batman.
It’s a bird, it’s a plane — it’s Superman, earning the title of “America’s favorite superhero,” according to new research. A survey of 2,000 Americans pinpointed respondents’ favorite heroes and Su…
nypost.com
This poll was done at Disney land in an avergers ride opening event and yet Superman still came first!!
The thing about both of these polls is that they were completed by the general public (not some niche pop culture site like superhero hype or many others) and at the end of the day it's the general public that fills those movie seats not just Gen Z-ers.
Now compare the boxoffice openings of MOS, Spidey homecoming and the Batman for further proof
MOS: 116.5 Homecoming 117 The Batman 132
It seems that Superman made the least right? Nope. MOS came out in 2013, Spidey in 2017 and The Batman 2022
and if you adjust them for inflation you'd get:
MOS 156 Homecoming 149 The Batman 140
Superman is clearly the winner and btw I didn't include the 12 mill MOS made from wallmart advance sales otherwise the number would be considerably higher.
Now why did I choose opening weekend numbers instead of movie totals? Well it's because it's a movie's opening numbers that determines the baseline strength of an IP while the total depends largely on quality and competition.
I constantly see people underestimating Superman's popularity (something I used to be guilty of) but the character continues to endure despite of the garbage that Singer, Snyder and CW threw at the character. Heck under David Zaslev's own admission Superman was left to languish yet it's Superman who was chosen to lead Gunn's DCU and not Batman and it's because Zaslev sees Superman as the character with the greatest potential.