With no clear source work, character or original recording attached to this clip, its life is entirely online as a reusable reaction sound. Short single word responses like this spread through soundboards and short form edits because they are easy to understand, fit almost any conversation and take up almost no time in a timeline. Creators reuse it as a neutral acknowledgement that can be played straight or ironically, which is why the same simple ok continues to work across memes, gaming clips and everyday reaction videos posted by different communities.