Chinese writing - that of Mandarin - does not seem anything like picture language as that is represented by Egyptian hieroglyphs. Nor does it seem ideographic in the sense that each character represents an idea. Is there is an accurate, brief characterisation of the language ? Perhaps there is not. I ask my question from a position of, as you will have realised, very considerable ignorance. But I would appreciate any guidance.
Is there is an accurate, brief characterisation of the language?
Considering it had developed over such a long period of time, it would be a trade-off between these two. The shortest, yet acceptable answer I can give is:
Written Chinese characters started with both pictorial and ideographic ones, but has grown more complex over history: Sometimes two characters that had the same sound would get confused and become the same character. Sometimes new characters are made combining the sound from one and meaning of another. Loanwords from sounds also exist throughout history. But the sounds also changed throughout history.
There are some Chinese characters that are called "象形字"， meaning that each of them representing a vivid picture, like "月（moon）"， “日（sun）”，“龟（tortoise )”, "马（horse）"， “鸟（bird）。”
There are some Chinese characters that are called “指事字” and "会意字". They are somehow like what you had in mind by "each character represents an idea". Examples of "指事字" are "一（one）"， “二（two）”， “三（three）” “上（up）”， “下（down）”. An examples of "会意字" is “采（pick）” that is a claw over a tree (木).
But the above mentioned characters only constitutes a small portion of Chinese character set.
According to this article: https://zhuanlan.zhihu.com/p/19929343
Chinese writing should be categorized as "morphosyllabic" or "logosyllabic",「语素音节文字」或意译作「意音文字」
文字类型（Types of Writing Systems）
音节文字（syllabary）/ 音拍文字（moraic writing）
语素音节文字（morphosyllabary）/ 语素音拍文字（morphomoraic writing）