Should the introduction of a thesis have figures/pictures?
I can't think of any reason in general that you should not do this if it makes sense in the context of the paper. If you can express the underlying concept better with a figure then it is better than to use words.
But an advisor might disagree, in the context of this paper. And an editor or reviewer of the paper might disagree. In that case, change it.
But the paper is yours. Do what you thing makes the most sense and makes the paper accessible to your audience.