Likable just means having pleasant or appealing qualities. Likable does not mean similar nor possible. You are probably getting confused with alike and likely. Alike means similar. For example: a look-alike, or double, is a person who closely resembles another person. Likely means reasonably to be believed or to be expected. Example: who is the most likely candidate for this job? A person who is seen as suitable for a position, someone who is considered for a job is " a candidate" A similar person would be an equally suitable person, an equally suitable candidate. In some context you can use the word "match". A match is a person or thing that is similar, equal to or suitable for another person, or a game or contest

If someone is likable, it means that you like them, or that they are easy to like. That's all it can mean. You aren't getting this word confused with 'likely', are you?

No - likable (or likeable) means they are friendly, kind, funny, or have other characteristics that would make most people like them. For 'possible person', you could use 'suitable'.

Someone it is easy to like, friendly.