If you look through this site you will not find any stock images
Stock images are photos, illustrations, videos, and audio files that can be bought on sites like iStock.
You'll have seen them before. Two business men shaking hands. A well groomed woman smiling and looking at a laptop. A graph of sales going up, up, up!
They are generic and bland, bland, bland!
Why would you want images like that on your website?
What does it say about you and your business?
Use something original for goodness sake!
Another point is if you are using images that other people can buy and use as well, that's duplicate content, and that won't get you any browny points with Google.