May I ask where you got these preconceptions? I ask because they are most certainly misinformed.
Let me try and start at the beginning with the first claim. " in Dark/Demon's Souls its always the same dull, boring, washed out levels."
Now Ive not played Demon's souls so anything I say will only be about Dark souls and you should also consider this a SPOILER WARNING. So youre complaint is that the levels are dull, boring, and washed out. Im unsure what you mean by washed out but may I ask, what is wrong with ruined castles and ruins that are crumbling due to the lack of mantinence over the centuries? What is dull and boring about vast lava filled caverns leading into a hidden city (lost izalith) in which a massive tree's roots are encroaching upon it? What is dull and boring about the light fueled city of the gods guarded by giants and silver knights that really turns out to be a darkness covered and lifeless place after its illusions are gone? What is dull and boring about entering a haunted city left to time for tens of thousands of years and unleashing one of the greatest threats of man when you must unflood the city to destroy its kings? All of that sounds like pretty epic stuff to me especially when one of the key themes in the game is "nothing lasts forever". Now the argument can be made that they're all the same in each playthrough but so what? I tend to reply games quite a bit
To also touch on the "same dude/dudette" idea, well no. The only thing you have in common is you are the chosen undead of your dimension. Similar to how in Skyrim you are always the Dragonborn. The chosen undead can be anyone, from any walk of life, and from anywhere. The only thing that must happen to be the chosen undead is you must be undead and you must escape the undead asylum. At that point you have the potential to be the chosen undead like so many before you but only the true chosen undead can claim the lordvessel and either link the flame or snuff it out (both are very personal choices and I don't equate either as the "good" ending to the game). I had one character whose backstory was an inquisitor in Catarina and he became a darkmoon blade so he could continue to hunt the guilty. I have another character who is an honorable Darkwraith from the great swamp and she likes to leave people presents before ruthlessly killing them for their humanity. I have another who was an illegal pit fighter in Astora and now wields a pair of Dragon bone fists while fighting people as an honorable Darkwraith. Then theres another character who was a Knight from Catarina and now he helps others through Jolly cooperation! These characters and more show one constant, the blank slate they give you allows you to build a character your way and roleplay them to your standards. The only thing you really have in common is that you escaped the undead asylum, your undead, and your in lordron. Why you pursue the quest of the chosen undead or even if you pursue it is entirely up to you, the player.
Now lets talk about this idea that if you don't know everything about the game you aren't playing it properly. Frankly that's nonsense. Many of the items, lore, covenants, armor, and weapons are there as exploratory rewards. You can finish the game without ever leveling up or upgrading any of your armor (Ive done it). The first few times you play through the game theres a big sense of accomplishment when you get something. For example the first time I found the Zwienhander and tried it out, I was bloody amazed. I still love that weapon, especially when you swing it and at the very end you hear that satisfying "Wham!" at the end of a swing. Hell half the fun of the game, for me, is just experimenting with new weapon/armor combinations in PVP environments. I love dueling and I love dueling with all kinds of crazy combinations. Some of them work, some of them don't, but I always have fun trying out something new. Getting back to your point, Im not sure what is "playing the game properly" because as my short character explanation shows you can play the game anyway you want to. You can be as knowlegable or unknowlegable as you want. You can cheap shot bosses, hell you can avoid some of them altogether if you like. You can go hunt the rich lore or not. Whatever you want to do. As long as you aren't cheating and your still trying to progress IMO your playing the game right. Sure youre going to die sometimes, but so what? We all did. What matters is getting passed that and not failing at the game. The only way to fail at the game is to put down the controller and never pick it up again and if you do that, its still ok because that just means dark souls wasn't for you.
I think you are looking at it the wrong way, or at least a very different way from how most people within the Dark souls community look at the game. To be fair, there are some things that Dark souls could do to be better for everyone like a better tutorial and a more comprehensive help and stats system that explains things better. Theres also the issue of other games, for lack of a better word, conditioning gamers to overlook simple warning signs like burned bodies on the dragon bridge, or blood stains on an elevator that leads up into spikes, or those pressure plates that littered in Sen's fortress.
At the end of the day, I love the game and if you don't like it that's ok. We all have different tastes and as one of my favorite commentators has said "Its ok to not like things just don't be a dick about it"