I can’t unlock my Apple Watch but I’m the owner of it

Why can't you unlock it?

If you have forgotten your Apple ID password, see this link and follow the instructions If you forgot your Apple ID password – Apple Support (AU)

If the device is activation locked and you are the original owner and have proof for that (receipt with serial number) you can start an activation lock request with Apple, see this link and follow the instructions How to remove Activation Lock - Apple Support

If you bought the device second hand and it is in activation lock to its original owner, all you can do is contact them to lift the activation lock. See also this user tip for reference https://discussions-kr-prz.apple.com/en/docs/DOC-250001038?commentId=250003637025