Baby hitting head on floor

My baby is 5 months and will be 6 months in a couple days. We have hardwood floor and usually let baby sit on the floor with a blanket . We are usually on the floor with her but we let her crawl and sit on her own as well sometimes. Sometimes as she’s playing she’ll move too fast and hit her head. She’s done this a couple times and she’ll usually cry for a few seconds. Of course we don’t want her to constantly hit her head but since she done this a couple times is it bad? Do you think it will affect her?