Is it healthy for someone who has never been kissed to date someone who's not a virgin?

It depends. Of course, you may have a different level of comfort than the other person. You might not want to do many things that s/he might enjoy or have done before. This person may or may not respect the level of comfort you have.

If this person can respect you and allow you to choose not to do things, well still being happy being with you, then yes, it's a healthy relationship.

An unhealthy relationship would be if they do not respect you and try to force it on you, and be unhappy with you if you refuse.

Be careful with what you choose, as you shouldn't be pressured to do something you do not want to do.