And here I am thinking that I should simply give some more compliments to my colleagues because I want to spread genuine good vibes. Even if it already has been “invented” by others, I am not hearing enough genuine compliments in the workplace.

Meaning that even if an idea already has been invented, that doesn’t mean there’s no room for your implementation of it. There still may be room.

I struggled with the same in academia. I found genuine beauty and value in improving something implemented. But I also felt a bit "stuck", as if I was just stuck in a groove unable to pedal up. I wasn't the only PhD that felt this way and spoke with others at the time about the feeling.

I think there's a point of diminishing returns where improving something isn't worth it. But I mean, if you're innovating at the level of a PhD, does anyone really know anything at all? You are, by definition, pushing the boundary of human knowledge.