Basically yes, with some fairly minor limitations.
1) Each force is made up of warbands. A warband consists of a hero and up to 12 troops,
all from the same list;
2) A force may have multiple warbands if you have the points for them. Although all warbands must be from one side (Good or Evil), you can mix ("ally") warbands from different army lists in a single force. Following point 1) above though, each warband must be from a single list;
3) There are some other limitations,for example most armies limit the number of bow-armed troops you are allowed to take.
For example Hobbit stats and Warband composttion, take a look here. Warbands are at the end of the file:
https://www.games-workshop.com/resources/PDF/Errata/The_Hobbit/Heroes_and_Villains_of_Middle-Earth_EN.pdf Note that some of the warbands are split a little uneasily at the moment - the Rivendell list from The Hobbit would not allow you to take figures from the Eregion and Rivendell list in the
LotR Free Peoples army book. That's only within a single warband though - you can have a warband from each list in your force. And really, the Rivendell split I just mentioned works out as cavalry in one warband, infantry in another.
There's also no rule that a warband has to fight as a unit - figures can support each other, banners and horns work for everyone in the force, and most heroes' abilities can affect any warband their force (there are exceptions, animal leaders for example, but that is listed for the affected heroes).