keyword optimisation

I optimized my primary keywords on meta title and description, H1, content on my home page, but other keywords ranking good, but the primary keyword not ranking on any where, even this keyword search volume only 1500, low competition. Any one know why this is happening?

Hey y'all... When I started my journey on YouTube, it was tough as nails. I was discouraged, facing all kinds of challenges, but I stayed the course. And you know what? I found my way, just like you can! The strategy I lay out below, it's like the map to success, my map to my success. But...

Should keyword density be higher then any other set of words in the content? Like if your keyword is "best computer repair" at 2% and a random word set of "Torque Screw Wrench" at 3% just happens to appear on the page cause your listing off parts or something. Is that confusing to google...

Is keyword optimisation a complete necessity for website traffic building.