Yes, Catholics must believe in the historical reality of Christ, Moses, Adam & EveAdam & Eve, et al.
Modernist heretics dispute their historicity, but magisterial teaching (DZ 1997) unequivocally says that Moses authored the Pentateuch (first 5 books of the Old Testament), by answering the following question in the negative:
Question 1. Whether the arguments accumulated by critics to impugn the Mosaic authenticity of the Sacred Books, which are designated by the name Pentateuch, are of such weight that, in spite of the very many indications of both Testaments taken together, the continuous conviction of the Jewish people, also the unbroken tradition of the Church in addition to the internal evidences drawn from the text itself, they justify affirming that these books were not written by Moses, but were composed for the most part from sources later than the time of Moses?
Reply: No.
The same Pontifical Biblical Commission affirmed that at least
The first three Chapters of Genesis contain narratives that correspond to objectively real and historically true events (rerum vere gestarum narrationes quae scilicet obiectivae realitati et historicae veritati respondeant), no myths, no mere allegories or symbols of religious truths, no legends.
If Moses were fictional, how could a fictional character author anything, let alone something that contains "historically true events"?
Also, the *Catholic Encyclopedia* isn't a magisterial document. *Imprimatur* simply means "let it be published," and *nihil obstat* means "nothing prevents [it from being published]." It doesn't make the publication an official magisterial pronouncement of the bishop(s) who gave the *imprimatur* and *nihil obstat*.