Shy baby?

Does anyone else have a shy, attached baby? My little guy is 15 months and sooo attached to his mama. I’m a SAHM, so he’s with me most of the time. I have dropped him off at a babysitter for 1 hour at a time and I’m told he cries the whole time. We don’t get out of the house much besides going to random stores and occasionally over to my sisters. He plays with his cousins and is totally fine when I’m there...he goes to other rooms and explores, but doesn’t really like to be held by anyone besides mom and dad. My family always comments on how shy he is and how he doesn’t like them (which I know isn’t the case). I don’t know how to help him not be shy or if it’s normal?