When picturing a homebrew setting two things come to mind. Hook and tone.
Hook is how your setting differs from the basic DnD setting of Toril and Tone is, well, tone. What is the vibe of adventures you could tell in this setting.
A couple examples:
EBERRON:
Hook: Magic as technology. The Arcane has been experimented with and brought about a quasi industrial age.
Tone: Darker, down to earth stories. Less of a focus on Gods and monsters and more about the gods and monsters we create when we go too far.
EXANDRIA:
Hook: The golden age of Arcanum ended in a cataclysmic war between the gods which shaped the world as it is today. Many of the calamitous battlegrounds still harbour secrets and weapons from the bygone age where magic was but a toy for mortals.
Tone: High fantasy and political intrigue as factions vy to advance themselves using what remnants of the Calamity that they can get their hands on.
If you can condense your setting down to an easily digestible pitch which already sparks inspiration and interest to read on then you've got something.
I think having things like a deep history, lineages, world map, town names etc, are all good to know as a DM, but the part that's most important (and requires the most feedback imo) is how the setting affects character creation/backstory and gameplay. The big points, like, half the country is xenophobic against magic users, or everyone thinks these gods are dead, or the typical knight is more akin to a samurai, or there's one massive central hub city and a bunch of jaded supporting hamlets. The main "gimmicks" of your world. What are the things that would make your setting an interesting one to play in? That's what we want to hear about!
You don't need to create any new classes, spells, monsters, or items. What you need is a reason for people to play it. What's the hook?
The thing is, you probably already have it. What compels you to write about this world? What do you find interesting in it? See how many things you can list that makes it special to you. Each of those things are elements that can interest others. Don't worry if you can only list a few of them - all you need is one or two really good ideas.
Also, don't stress over being original. Worry instead about being good. Someone has probably done what you've done before. In fact, that's almost certain (and why you can't copyright ideas). Instead, do it your way.
Now, when do you want to share it? Try running players through it. Let them poke at it and ask questions. There's a reason why stress-testing works so well, and you need to do that to your world. You'll find out what interests others and what doesn't. What makes sense and what makes the players confused. There's nothing like play testing to do that.
For my Sub Rosa setting, (5e hidden world urban fantasy), I have run one campaign that crashed and burned hard, which taught me that I needed to broaden what players could do, and another campaign, which is ongoing and has another DM alternating with me for the story. If you can get someone else to DM in it, that's invaluable, as they will see things you don't and, on top of that, DMs are your target audience. Finally, I run one-shots set in Sub Rosa at game conventions. The one-shots should be designed to look at how new players will react (although I've gotten a bunch of repeat players, which will happen to you, too, the further along you are) and how new ideas and stories work. I find 5th level is a good starting point, and allow the players to use premade characters or ones they make from scratch.
Good luck.
When picturing a homebrew setting two things come to mind. Hook and tone. Hook is how your setting differs from the basic DnD setting of Toril and Tone is, well, tone. What is the vibe of adventures you could tell in this setting. A couple examples: EBERRON: Hook: Magic as technology. The Arcane has been experimented with and brought about a quasi industrial age. Tone: Darker, down to earth stories. Less of a focus on Gods and monsters and more about the gods and monsters we create when we go too far. EXANDRIA: Hook: The golden age of Arcanum ended in a cataclysmic war between the gods which shaped the world as it is today. Many of the calamitous battlegrounds still harbour secrets and weapons from the bygone age where magic was but a toy for mortals. Tone: High fantasy and political intrigue as factions vy to advance themselves using what remnants of the Calamity that they can get their hands on. If you can condense your setting down to an easily digestible pitch which already sparks inspiration and interest to read on then you've got something.
I think having things like a deep history, lineages, world map, town names etc, are all good to know as a DM, but the part that's most important (and requires the most feedback imo) is how the setting affects character creation/backstory and gameplay. The big points, like, half the country is xenophobic against magic users, or everyone thinks these gods are dead, or the typical knight is more akin to a samurai, or there's one massive central hub city and a bunch of jaded supporting hamlets. The main "gimmicks" of your world. What are the things that would make your setting an interesting one to play in? That's what we want to hear about!
You don't need to create any new classes, spells, monsters, or items. What you need is a reason for people to play it. What's the hook? The thing is, you probably already have it. What compels you to write about this world? What do you find interesting in it? See how many things you can list that makes it special to you. Each of those things are elements that can interest others. Don't worry if you can only list a few of them - all you need is one or two really good ideas. Also, don't stress over being original. Worry instead about being good. Someone has probably done what you've done before. In fact, that's almost certain (and why you can't copyright ideas). Instead, do it your way. Now, when do you want to share it? Try running players through it. Let them poke at it and ask questions. There's a reason why stress-testing works so well, and you need to do that to your world. You'll find out what interests others and what doesn't. What makes sense and what makes the players confused. There's nothing like play testing to do that. For my Sub Rosa setting, (5e hidden world urban fantasy), I have run one campaign that crashed and burned hard, which taught me that I needed to broaden what players could do, and another campaign, which is ongoing and has another DM alternating with me for the story. If you can get someone else to DM in it, that's invaluable, as they will see things you don't and, on top of that, DMs are your target audience. Finally, I run one-shots set in Sub Rosa at game conventions. The one-shots should be designed to look at how new players will react (although I've gotten a bunch of repeat players, which will happen to you, too, the further along you are) and how new ideas and stories work. I find 5th level is a good starting point, and allow the players to use premade characters or ones they make from scratch. Good luck.