I admit, I lost interest in Superman years ago, possibly decades, but he is the first superhero I can remember.
My first exposure to Superman was probably through the George Reeves TV show. He was also the first comic book super hero I can remember.
That was back i the early days of the Silver Age when Superman was a genre all by himself. He starred in two comics of his own (Superman and Action). He shared World's Finest with Batman. He was a supporting character in Lois Lane and Jimmy Olsen. As Superboy, he had his own book and was a backup for the Legion of Superheros. He was also a member of the Legion and the Justice League of America.
The Superman family was huge. It included Superman/Superboy, Superman's co-workers, his adopted parents (who died before he came to Metropolis), his birth parents (who were featured a number of times), his girl friend and best friend from his Superboy years, his cousin Supergirl and her family, his dog, a monkey from Krypton, Supergirl's cat and horse (who was really a centaur), a mermaid he'd dated in college, the bottled city of Kandor, the prisoners of the Phantom Zone, and Lex Luthor.
The list of Superman's powers was lengthy. Besides the obvious super strength, flight, and invulnerability, he could see through anything (except lead). He also had telescopic vision, microscopic vision, and night vision. Using super hearing and super ventriloquist, he could talk with anyone anywhere on Earth. His super breath could freeze things or simply blow them over. He could move faster than the speed of light. If he flew that fast while spinning clockwise he went into the future. Spinning counter-clockwise took him into the past.
With all of those powers, there was little to challenge him so the writers often resorted to imaginary stories or dreams. Other times he traveled to worlds with a red sun where he lost his powers or was temporarily altered with Red Kryptonite.
All of this went out of style by the late 1960s and efforts were made to make Superman relevant. He was given longer hair. Kryptonite was destroyed. Imaginary stories were no longer written. Lois Lane was given a makeover and made a few appearances in a bikini. Superman went from writer to newscaster. He also began facing opponents who could physically challenge him. At the same time a plot formula was introduced and rigidly adhered to. The result was mind-numbingly boring.
In the early 1980s the DC universe was rebooted and Superman's history was rewritten. Almost all of the Superman family was erased. Superman himself was de-powered. He couldn't even fly through space without an oxygen supply.
In the 1990s he was killed and resurrected and finally got married.
In the 2000s, his history was rewritten again and the marriage never happened.
In the 1970s, Superman made his premier in a big-budget movie. The franchise lasted through four movies but got sillier as time went on. The character was rebooted in the 2000s in a movie that made money but left audiences unsatisfied. All of the summer excitement that year went to Pirates of the Caribbean 2 which came out a week after Superman Returns and buried it.
A new reboot is about to come out. It promises to be darker than the previous ones. We will see.
Still, it's impressive that the character is still popular at 75.