Is there a word for someone that gets constantly deceived and never learns? ex. Charlie Brown always falling for Lucy's "pull away the football" gag? [duplicate]

I was thinking that it would be useful to have some potent way of expressing that a person, population, nation, organization, species.. Any entity. Is susceptible to being constantly duped by some trick and they either never figure it out or it takes a long time for them to slowly put the pieces together. If there isn't a word, how could it be phrased?

The classic example below.

Solution 1:

Two different words spring to mind:

Naive

https://dictionary.cambridge.org/dictionary/english/naive

too willing to believe that someone is telling the truth, that people's intentions in general are good, or that life is simple and fair

Gullible

https://dictionary.cambridge.org/dictionary/english/gullible

easily deceived or tricked, and too willing to believe everything that other people say

Solution 2:

Sucker.

sucker n Slang
One who is easily deceived; a dupe. _{TFD Online}

Solution 3:

The term for this in American English (where Charlie Brown comes from) is patsy.

patsy n Slang
A person easily taken advantage of, cheated, blamed, or ridiculed.
_{TFD Online}