WordNet sense 1 (free from danger or the risk of harm):

safe

WordNet sense 2 (lacking significance or impact):

insipid

WordNet sense 3 (having no adverse effect):

innoxious

WordNet sense 4 (not causing disapproval):

unobjectionable

WordNet sense 5 (lacking intent or capacity to injure):

innocent

WordNet sense 6 (not causing or capable of causing harm):

harmless