に過ぎない means “no more than,” “nothing more than,” or “merely.” It limits the value, status, amount, or significance of something and often conveys that it should not be overestimated. It commonly follows a noun or a verb in plain form. The construction is generally neutral to formal and is frequent in explanations, written statements, and careful speech. A な-adjective does not normally attach directly; an appropriate form such as である may be needed in formal constructions.