Our brains are predisposed to pay attention to faces. When we see people on pictures it makes us feel like we’re actually connecting with them, and not just buying something.
Nevertheless, a lot of businesses are notorious for their overuse of “happy-faces” pictures, which are supposed to make people trust them. But keep in mind, that purely decorative photos often annoy users and don’t usually add any design value. Try to use good-quality photos of your real staff, if that is needed.
To sum up, try to test your design on different devices and ask users to share feedback. When people interact with websites, they expect a perfect user experience.