DX11 Feature Level 10.0 Required To Run This Engine

DirectX 12 is backwards compatible with DirectX 11, but there are some caveats and limitations to be aware of:

DirectX is not fully forward or backward compatible across major versions. While DirectX 12 can run applications built for DirectX 11, it does not support all DirectX 11 features and functionality.  

Games and applications specifically coded to use DirectX 11 may not automatically work when DirectX 12 is installed. They may require updates or patches from the developer to utilize DirectX 12 capabilities.
Older graphics hardware and drivers may lack full support for DirectX 12 features, even if DirectX 12 is installed on the system. This can cause compatibility issues when running DirectX 11 applications on DirectX 12.
Developers have the option to support both DirectX 11 and 12 APIs in their applications to ensure compatibility across a wide range of hardware configurations.

In summary, while DirectX 12 aims to maintain backwards compatibility with DirectX 11, there can be gaps that prevent seamless operation of DirectX 11 applications on systems with only DirectX 12 installed. Developers may need to explicitly add support for both APIs to guarantee functionality

the error appears immediately as soon as I start the game (before that I hear a few seconds of music from the main menu)

Yes, I've updated them too.

I downloaded the game directly from steam

• Have you tried running in Clean Boot to find if there is a conflict with a Service or Starup App ? I doubt that this will help, since there is nothing in my startup except windows defender , but, I'll try
• If using a URL\Internet type desktop shortcut created during the installation of the game, have you tried launching the game

from the main .exe in the games install directory, or launching from the games title in your Steam (or EPIC, etc) library ?

  I tried to launch the game both through a shortcut, through "play" in steam, and run the executable file of the game. all this led to an error

• Are all of your motherboard drivers (chipset, etc), up to date too ?

  yes, I've updated them too
  

• What are the titles of some other games you are having problems with ?
  Not an answer to your question, but...
  Is the -d3dx11 command verifiable as working for some other users, or just a suggestion from another site ?

From what I see on Steam, this version of Ark is still a DX10\11 game, so no command should be required.

• The idea that Win10\11 having DX12 installed may cause games that use DX11\10 or even DX9 to have compatibility issues may be

true if the developers borked their upgrade from older DirectX to a newer DirectX (making the game the problem), but is not generally correct.
The only times when DX is the source of incompatibility is when old hardware (eg- Intel HD 2000\3000) is not capable of using that version,

or the user is still using an old Windows version that is limited to DX9\10.

Many older games use an older DirectX, eg- DX9 for low graphics settings, and DX10 for high settings, but many (most ?) recent

release DX12 games are DX12 exclusive. Others, such as Fortnite, have been upgraded to DX12 exclusive.

• 'Backward' compatibility is not a thing with DX.

It is the game, not Windows, and not the user (other than in the games settings) that selects which DX files are used.

Win10\11 does not only have DX12, and the different versions of DirectX are all independent of one another.

Win10\11 has all versions of DX9\10\11&12, however Win11 does not install with all available older sub-versions of DX

(maybe because games generally reinstall DX while they are installing, MS decided to leave it up to the games ? ),
so when using a clean install of Win10\11 running the DX Web Installer or using the DX Redist (June 2010) is a good idea to

assure all of the available DX files for older games are installed.
(btw - Did you do the second stage, and run the dxsetup.exe found in the folder you extracted the files to ? )

.

I'm not arguing with what you wrote, but I have objections.

I have a laptop that also has dx12 installed, but the game runs fine on it.

-d3dx11 in the launch parameters should have forcibly started the game on dx11 , but it did not affect in any way.

It's interesting that it works on your laptop. I think that reflects the different video hardware which maybe better backward supports DX11. Sorry, but I have no ideas as to what else you can do at this point. Maybe someone will. Good luck.

I'm not arguing with what you wrote, but I have objections.

I have a laptop that also has dx12 installed, but the game runs fine on it.

-d3dx11 in the launch parameters should have forcibly started the game on dx11 , but it did not affect in any way.