Forgot to mention, but Superman is totally my favorite. The philosophical depth that comes with being the first superhero, plus his name coming from Nietzsche and having all sorts of implications, results in some very meaningful stories. Of course they're spaced among many that are just regular sci-fi, but those are good too. Since you mentioned Superman specifically, I'll say check out his various origin stories. Yes, there are a bunch and they're all sorta canon (long story), but they're also all good, and all easy for newbies to understand. The main ones I'd recommend are Superman #1 from 1939 (just a single issue, an expanded version of the earlier origin from Action Comics #1). I mention this specifically because you seem to be into old stuff. Not everyone gets it, but I enjoy a lot of stuff from the '30s and '40s. (Though Namor and The Human Torch from Marvel were the best at the time.) Later Superman origin stories include Man of Steel from 1986, Superman: Birthright from around 2003, Superman: Secret Origin from around 2009, and Superman and the Men of Steel from 2011. There might be one more since. They're rebooting too damn often for me lately and I can't keep up. I'd recommend Man of Steel above others, both because it's the first reboot, but also because the point is that it covers his whole history to that point, and I like how it does six separate but related stories. They're all good.
Other ones I like that are either very classic or just easy to understand but still good include The Death and Return of Superman, Superman: Peace on Earth, Superman: Secret Identity (not actually canon, but like what if he existed in the real world), Superman: Red Son (alternate universe where his spaceship lands in Soviet Russia), and Lex Luthor: Man of Steel. Admittedly, a lot of my favorite Superman stories are hardcore into autistic continuity (Like Superman Beyond 3D), but these are good places to start.
Also, note that when I talk about reboots, none of them are true reboots, but it's hard to explain how things semi-reset but actually everything ever is canon, even the things that get overwritten by other things. You'll get it eventually.
Also, why not just get into tv shows? Lots of long running ones that could keep you occupied forever. Since I'm talking about comics, I have to recommend the DC Animated Universe, which in some ways is better than the comics, and much easier to understand. The live action universe sucks though except for a couple seasons. Smallville was alright and that has like 220 hour long episodes, but the levels of homoeroticism are off the charts.
Just get into anime like everyone else here. Start with casual shit. Dragon Ball is great and has like 700 episodes at this point. Start at the beginning and if you stop liking what you see then just stop watching, because generally the newer stuff is worse, but the first two or three hundred episodes are great.
>Pics used to illustrate interesting continuity in comics. Future President Lex Luthor once went back in time (which he can do quite easily, once by using some cans of orange juice and a few lightbulb filaments) and accidentally prevented past-Superman, Superboy, who had also gone back in time but left from an earlier period, from stopping the assassination of President Lincoln. But it turns out it's okay because later it turned out that Lincoln was actually Brainiac all along, and John Wilkes Booth was actually adult Superman, traveling back in time again from further in the future, after having been turned into a Metallo.