Checking your actual landing page ( https://propertywebbuilder.com ) and my opinion is... that it isn't a very good landing page. The sizing and spacing are awkward and blocky, your color scheme clashes with your images, the images are generic and tacky, everything is too big and wide, etc. Maybe because you worked on it you feel that it is a great modern style landing page, but that isn't how it reads to me (and seemingly to other people as well).

Maybe you look at a SIMPLER site like https://tom.preston-werner.com/ and mistakenly equate that with a "worse" landing page. Actually though this simple page has bullet proof styling, and slapping some stock images on it like you did on your page wouldn't make it better, it would make it way worse.

Rather than looking for an external factor like a "mythical uncanny valley" to explain your landing page's poor performance, look inwards at your individual styling and what could be improved.