The Minions can function within any time period as long as they serve the Big Boss. What "Minions & Monsters" does is still play to that concept while still paying a heavy tribute to early film history. While the first 1/3 builds up the mythology, the 2nd 1/3 is interesting in that it tells a creative original story about the Minions in Hollywood. The story does get very meta in the end (and in retrospect...the beginning as well) but it is a love letter from the Paris based Illumination back to the beginnings of Hollywood.

The aspect of the Minions is always trying to understand what they are saying and how their shenanigans will unwind everything they try to accomplish for their master: Gru. With "Minions: The Rise Of Gru",the story is brought back to the villain's tween years where he is just trying to find his identity but also looking for mentors.