Yeah, it has that shade, like, when you say "много людей" it is more "many, lots of people" and "многие люди" is "all kinds of people, quite a number". "Многие" is much more often used when you need to say something like "Many people like/do/think something", though you can also use "много". Besides, with "многие" you don't need "люди": it can do without this ("Many are responsible for this" - the same in English).
If you need "many of the ...", only "многие" works without rephrasing: "Многие из нас остались" = "Many of us have remained". You can, of course, say something like "Много из нас осталось", but er.. not as good, and grammatically it is more like "Of all of us, many have remained"