Do we ignore the language differences interpreting Moses being not a man of words (לֹא֩ אִ֨ישׁ דְּבָרִ֜ים אָנֹ֗כִי)?
וַיֹּ֨אמֶר מֹשֶׁ֣ה אֶל־יְהוָה֮ בִּ֣י אֲדֹנָי֒ לֹא֩ אִ֨ישׁ דְּבָרִ֜ים אָנֹ֗כִי גַּ֤ם מִתְּמוֹל֙ גַּ֣ם מִשִּׁלְשֹׁ֔ם גַּ֛ם מֵאָ֥ז דַּבֶּרְךָ אֶל־עַבְדֶּ֑ךָ כִּ֧י כְבַד־פֶּ֛ה וּכְבַ֥ד לָשׁ֖וֹן אָנֹֽכִי׃
But Moses said to the LORD, “Please, O Lord, I have never been a man of words, either in times past or now that You have spoken to Your servant; I am slow of speech and slow of tongue.” (Exodus 4:10, JPS)
When people watch movies such as the Ten Commandments, the differences in languages aren’t portrayed. While Moses’s mother probably taught him Hebrew, he undoubtedly spoke Egyptian in Pharaoh’s court, although his place subordinate to Pharaoh may have discouraged outspokenness. Then, he spent 40 years in Midian, away from all that. Midian may have spoken an Old Canaanite language much like Hebrew.
While the text states than Moses (מֹשֶׁ֣ה) was never “a man of words,” the lack of words may have also been related to the language barriers from being away for 40 years. Apparently Aaron, living all that time in Egypt, was fluent in both Hebrew and Egyptian. While we have basically interpreted "not a man of words" correctly, have we ignored the contribution of the different languages.