If you describe someone as naive, you think they lack experience and so expect things to be easy or people to be honest or kind.

What is a naive person like?

having or showing unaffected simplicity of nature or absence of artificiality; unsophisticated; ingenuous. having or showing a lack of experience, judgment, or information; credulous: She's so naive she believes everything she reads. He has a very naive attitude toward politics.

What causes a person to be naive?

Someone might call you “naive” if you are overly trusting or lack experience in the world. Naive people are often so trusting of others around them that their natural innocence results in them getting cheated or hurt.