Even if some major events of your world do have relevancy, I believe making an entire timeline is a bit too far, considering that you have to add all of those thousands of years of countless events to your plotline at some point, and perhaps connect it to other details of your own worldbuilding. I'm pretty sure you need to have expanded quite a lot in your worldbuilding to be able to do such a thing.
Is there a reason to go to all that effort?
I have one word for you, just one word: Continuity
Let's consider three levels of effort:
I'm just building a world, it's a cool world! It's a little bit steam punk! But it also exists just in the moment — a snapshot of its history. Does this need a timeline? Probably not.
I'm only building the world, but not writing a story. However, that includes a history that brings the world to the "present." Does this need a timeline? Yes, but it needn't be seriously detailed. It'll include large events that shifted big things: geology, politics, cultural development, etc.
The whole point of building my world is to write a fantastic ten-novel series that will be turned into an Amazon Prime series and make me gobs of money! Does this need a timeline?
And there's the crunch. Heck, yes, you'll need a timeline — and a pretty detailed one, too.
When writing a story you have multiple characters involved in multiple plots all going on "at the same time" over, potentially, long periods of time. Things that happened in the past are relevant to the future and different aspects of that past may be relevant to some present characters where other aspects are known or have affected yet another group.
Continuity
Unless you have one spectacular memory, the only hope you have of maintaining continuity during your story is a good timeline. How you create and manage that timeline is your business. I've heard of index cards, rolls of calculator tape, word processors/spreadsheets... I'd be shocked if there wasn't software in the world designed to do it. There is no one solution that's right for everyone.
In conclusion, a timeline is just another note, one of a bazillion notes a good author creates when developing a great world with a fantastic story.
If you don't want to be bothered, there's no one on the whole planet who will judge you for it. If you're looking for permission to not do it, allow me to bless your worldbuilding efforts and tell you it's OK. But if you want to write a complex story in a complex world... you should seriously consider building a timeline — no matter how complex it gets.
The Cats of Queen Berúthiel
In addition to the continuity issue, a timeline also helps make a fictional world feel lived-in. Not important for a one-off short story, but important for anything longer imo. Even if your reader never sees it, you the author can use the timeline to inject a lot of information that makes the world feel REAL. One-off throwaway lines that add depth and a bit of interest. Stacked up across a book or books it can make a story much better than it otherwise would. So not only does the timeline let you keep track of what's important to the story, it also lets you inject other things that keep your characters and setting interesting to the reader.
Tolkien was a master of this and it's no surprise that he spent literal decades writing histories about all sorts of things that may or may not have ended up in the final books. "He is surer of finding the way home in a blind night than the cats of Queen Berúthiel" says Aragorn to Gandalf. The reader has NO IDEA who that is. It was decades before they ever would understand the full context of the quote (Queen Berúthiel gets fleshed out a bit in Unfinished Tales). But even without full context it paints a lovely picture using in-universe terminology and adds an air of mystery and interest to the story overall.
I'll also point out that you don't need thousands of years of countless events. If I say "fiddling while Rome burns" most (english speaking/european) people know it's a reference to Nero, who was a roman emperor at some point in Roman history who allegedly played music while Rome burned. But who remembers Emperor Claudius who came right before Nero? Or Galba, who came after? Or even The War of the Four Emperors sparked by Galba's ascension? Tolkien liked history, and his characters were incredibly knowledgeable compared to the "average" of middle earth (hobbits notwithstanding). But a thousand-year timeline might need only a dozen events and people to make a world feel "real" until you get to near-present. After all, a thousand years is a loooong time, and for most people what happened from their grandparent's lives onward is all that they're likely to really know about. Doubly so in a universe without formal education!
Is there a reason to go to all that effort?
What's the goal?
If the world building and cultural history of your own world sounds like too much effort, maybe you are not "creative"? No need to invent the wheel when there are genres and highly-specific sub-genres with ready-made worlds built-in.
Narrative-tropes include settings the reader already knows. An author uses stock characters in situations that don't require a backstory, shorthand so the reader can go straight to the action.
'Slop' fiction is not new. Worlds can be shallow and broad like Star Wars, where honestly the less backstory the better because it only embarrasses from the lack of coherency. That's not the point.
'Intelligent' world building is also appealing, where the setting is narrow (a world-building conceit that defines the story), or deep (the story evolves from the themes, characters are representative of their environment).
It's not a binary. Readers who enjoy slop-punk-pew-pew-yee-haw can also enjoy ponderous-god-fated-galactic-dynasties.... Sometimes it's not about the details, it's about how the story is told.
World building without a story might be its own creative goal. There are no constraints on what should or should not be significant. The inclusion of events is up to the author.
This is Writing, where world building is in service to a story. the presumption is that world-building is a communication tool, and the author mostly hints at a submerged iceberg that is not directly seen in the finished work, but is evident through subtext, environmental storytelling, and culture-coded details.
Sophisticated world-building is subtle and pervasive, punk world-building is fast and loud. Some genres promise 'cozy' to signal scope and scale, while others are signaling their credentials within literary or historic context.
World-building should not lore-dump the begats of a thousand-year reign of un-eventful rulers. That is an exercise in filler-content. We have AI for this now, it is not even creative just faking the obsessive completeness of fanfiction.
If a story requires a coherent timeline of events, the author should plot (at least) the parts that are relevant, or that need clarity. But respect the reader's suspension of disbelief. The goal is to spark their imagination so the reader believes they know the world already. It's always better to allow them to fill in the gaps with their own possibilities, than to kill imagination with a lot of filler and trivia.
